CVE-2026-6607
Description
A security vulnerability has been detected in lm-sys fastchat up to 0.2.36. This issue affects the function api_generate of the component Worker API Endpoint. The manipulation leads to resource consumption. The attack can be initiated remotely. The exploit has been disclosed publicly and may be used. The identifier of the patch is c9e84b89c91d45191dc24466888de526fa04cf33. It is suggested to install a patch to address this issue. Commit ff66426 patched this issue in api_generate of base_model_worker.py and did miss other entry points.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
fschatPyPI | <= 0.2.26 | — |
Affected products
1Patches
1c9e84b89c91dfix: wrap remaining blocking calls with asyncio.to_thread to prevent DoS
3 files changed · +3 −3
fastchat/serve/base_model_worker.py+1 −1 modified@@ -215,7 +215,7 @@ async def api_generate(request: Request): async def api_get_embeddings(request: Request): params = await request.json() await acquire_worker_semaphore() - embedding = worker.get_embeddings(params) + embedding = await asyncio.to_thread(worker.get_embeddings, params) release_worker_semaphore() return JSONResponse(content=embedding)
fastchat/serve/huggingface_api_worker.py+1 −1 modified@@ -233,7 +233,7 @@ async def api_generate(request: Request): params = await request.json() worker = worker_map[params["model"]] await acquire_worker_semaphore(worker) - output = worker.generate_gate(params) + output = await asyncio.to_thread(worker.generate_gate, params) release_worker_semaphore(worker) return JSONResponse(output)
fastchat/serve/multi_model_worker.py+1 −1 modified@@ -109,7 +109,7 @@ async def api_generate(request: Request): params = await request.json() await acquire_worker_semaphore() worker = worker_map[params["model"]] - output = worker.generate_gate(params) + output = await asyncio.to_thread(worker.generate_gate, params) release_worker_semaphore() return JSONResponse(output)
Vulnerability mechanics
Generated by null/stub on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
9- github.com/advisories/GHSA-5h65-jx66-j7p5ghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-6607ghsaADVISORY
- gist.github.com/YLChen-007/87216a2d97a882d619e11dc67cd473b5nvdWEB
- github.com/lm-sys/FastChat/commit/c9e84b89c91d45191dc24466888de526fa04cf33nvdWEB
- github.com/lm-sys/FastChat/issues/3833nvdWEB
- github.com/lm-sys/FastChat/pull/3835nvdWEB
- vuldb.com/submit/792227nvdWEB
- vuldb.com/vuln/358242nvdWEB
- vuldb.com/vuln/358242/ctinvdWEB
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