vLLM: Security Check Bypass via assert Statement in Activation Function Loading Allows Arbitrary Code Execution
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.7%
exploitation probability
0.7%top 49% of all CVEs
observed exploitation
nono source reports it
vLLM is an inference and serving engine for large language models (LLMs). Prior to 0.22.0, an assert-based security check in vLLM's activation function loading allows any unauthenticated attacker to achieve arbitrary code execution on the server by publishing a malicious HuggingFace model, when vLLM runs in Python optimized mode (python -O or PYTHONOPTIMIZE=1). This vulnerability is fixed in 0.22.0.
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Affected products
vllm-project · vllmReferences
https://access.redhat.com/errata/RHSA-2026:36005https://access.redhat.com/errata/RHSA-2026:36006https://access.redhat.com/security/cve/CVE-2026-41523https://bugzilla.redhat.com/show_bug.cgi?id=2491582https://github.com/vllm-project/vllm/commit/b3c7ffcab82c2439726f8cb213800f6f38c023d3https://github.com/vllm-project/vllm/security/advisories/GHSA-q8gq-377p-jq3rhttps://huntr.com/bounties/dcb05b04-e625-41e7-adbc-bbae0cc2d64chttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-41523.json