PatchTheCVECVE-2026-34756: vLLM is an inference and serving engine for large language models (LLMs)
CVE-2026-34756 is a medium-severity flaw (CVSS 6.5) affecting vllm. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
vLLM is an inference and serving engine for large language models (LLMs). From 0.1.0 to before 0.19.0, a Denial of Service vulnerability exists in the vLLM OpenAI-compatible API server. Due to the lack of an upper bound validation on the n parameter in the ChatCompletionRequest and CompletionRequest Pydantic models, an unauthenticated attacker can send a single HTTP request with an astronomically large n value. This completely blocks the Python a
Why this priority
- No elevated risk signals yet
A fixed release or distro patch exists.
Last updated 2026-08-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-34756?
vllm: upgrade to 0.19.0. Exact commands for each OS are on this page.
Is CVE-2026-34756 being exploited?
CVE-2026-34756 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-34756 affect?
CVE-2026-34756 affects vllm. Severity is medium (CVSS 6.5). vLLM is an inference and serving engine for large language models (LLMs). From 0.1.0 to before 0.19.0, a Denial of Service vulnerability exists in the vLLM OpenAI-compatible API server. Due to the lack of an upper bound validation on the n
How urgent is CVE-2026-34756?
Priority 32/100. No elevated risk signals yet.
Software pages
Python vulnerabilities · OpenAI and LLM tools vulnerabilities
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