CVE-2026-105756: DoS via unvalidated cache_salt in vLLM before 0.30.0 · ZeroHour

CVE-2026-105756

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DoS via unvalidated cache_salt in vLLM before 0.30.0

CVSS 3.1

6.5 medium

EPSS

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Published

Oct 5, 2026 (3d ago)

Modified

Oct 8, 2026

AI analysis

vLLM before 0.30.0 accepts a non-empty cache_salt on OpenAI-compatible requests without enforcing the character and length limits required by the LMCache-MP IPCCacheServerKey consumer. On servers using that connector, a salt with a forbidden character or excessive length raises an uncaught ValueError during scheduler cache lookup, which terminates EngineCore and denies service to every concurrent user. The attacker needs network access and low privileges; there is no confidentiality or integrity impact, and only LMCache-MP deployments are affected. The flaw is fixed in vLLM 0.30.0. It is not in CISA KEV and no public proof-of-concept is known; a related headline about unauthenticated remote code execution in LMCache describes a different issue.

What to do: Upgrade vLLM to 0.30.0 or later. Until then, disable the LMCache-MP connector or block untrusted clients from setting cache_salt on the OpenAI-compatible API, and restart any EngineCore process that has already crashed.

Affected

vLLM	prior to 0.30.0

Estimated exposure

—No basis for an estimate.

Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.

Description

vLLM is an inference and serving engine for large language models. Prior to 0.30.0, OpenAI-compatible request models accept a non-empty cache_salt value without enforcing the character and length restrictions required by the IPCCacheServerKey consumer in LMCache-MP. On deployments using the LMCache-MP connector, a salt that contains a forbidden character or exceeds the permitted length can raise an uncaught ValueError during scheduler cache lookup, causing EngineCore to terminate and denying service to all concurrent users. This issue is fixed in version 0.30.0.

Vendors: vllm
Products: vllm
Ecosystems: pip
Weakness: CWE-20, CWE-248
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
GHSA: GHSA-2823-qmq8-rwvj (medium)

NVD CVE.org GitHub PoCs EPSS (—)

CVE-2026-105756

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