LangChain MongoDB has NoSQL Operator Injection in MongoDBSaver.list() leading to cross-tenant data exposure

# Executive Summary

A NoSQL injection issue exists in the langgraph-checkpoint-mongodb and langgraph-store-mongodb libraries. MongoDBSaver.list() and MongoDBStore.search() methods accept a filter parameter that is incorporated into MongoDB queries without sufficient validation. Because MongoDB query operator keys (those prefixed with $) are not rejected during filter construction, a caller with control of the filter input can embed MongoDB query operators directly into the query.

---

CVSS

Details

CVSS 4.0

| Field | Value | |---|---| | CVSS Version | 4.0 | | Vector String | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N | | Base Score | 7.1 (High) |

| Metric | Value | Rationale | |---|---|---| | Attack Vector (AV) | Network | Triggerable remotely via API | | Attack Complexity (AC) | Low | No special conditions required | | Attack Requirements (AT) | None | No prerequisite deployment or execution conditions | | Privileges Required (PR) | Low | Authenticated caller of the checkpoint/store API | | User Interaction (UI) | None | No user action required | | Vulnerable System Confidentiality (VC) | None | No direct impact on the vulnerable component itself | | Vulnerable System Integrity (VI) | None | Read-only access | | Vulnerable System Availability (VA) | None | No service disruption | | Subsequent System Confidentiality (SC) | High | Full access to other tenants' checkpoint data | | Subsequent System Integrity (SI) | None | No write or modification capability | | Subsequent System Availability (SA) | None | No service disruption to downstream systems |

CVSS 3.1

| Field | Value | |---|---| | CVSS Version | 3.1 | | Vector String | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N | | Base Score | 7.7 (High) |

| Metric | Value | Rationale | |---|---|---| | Attack Vector | Network | Triggerable remotely via API | | Attack Complexity | Low | No special conditions required | | Privileges Required | Low | Authenticated caller of the checkpoint/store API | | User Interaction | None | No user action required | | Scope | Changed | Impact crosses tenant boundaries | | Confidentiality | High | Full access to other tenants' checkpoint data | | Integrity | None | Read-only access | | Availability | None | No service disruption | ---

Affected

Packages | Package | Distribution | Affected Methods | Affected Versions | |---|---|---|---| | langgraph-checkpoint-mongodb | PyPI | MongoDBSaver.list(), MongoDBSaver.alist() | < 0.3.0 | | langgraph-store-mongodb | PyPI | MongoDBStore.search() | < 0.4.0 | ---

Advisory

FAQ

How do

I know if I am affected?

You are likely affected if all of the following are true: 1. Your application uses langgraph-checkpoint-mongodb or langgraph-store-mongodb. 2. Your application calls MongoDBSaver.list(), MongoDBSaver.alist(), or MongoDBStore.search() with a filter argument. 3. Any part of that filter argument is derived from user-controlled input — for example, HTTP query parameters, request body fields, or agent tool arguments. 4. You operate in a multi-tenant context where the filter is used to enforce per-user or per-tenant data isolation.

If the filter argument is constructed entirely from trusted, server-side values, the practical risk is lower, but upgrading is still recommended.

How do

I fix the issue?

Upgrade to the version of langgraph-checkpoint-mongodb and langgraph-store-mongodb. If you cannot upgrade immediately, apply the following mitigation: in your application code, before passing any user-controlled input to the filter parameter, remove or escape MongoDB Query metacharacters such as “$”.

---

Acknowledgements

Thanks to Kenichi Kawaguchi for responsibly disclosing this issue via the GitHub Security Advisory program on the langchain-mongodb repository.

---

Revisions

| Date | Description | |---|---| | 2026-06-05 | Initial advisory published |