cvedb.io
CVE-2026-34756
MEDIUM · CVSS 6.5
EPSS exploitation probability: 0%
Published 2026-04-06T16:16:36.610 · Last modified 2026-06-30T03:18:57.883

Summary

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 asyncio event loop and causes immediate Out-Of-Memory crashes by allocating millions of request object copies in the heap before the request even reaches the scheduling queue. This vulnerability is fixed in 0.19.0.

Affected products

vllm — vllm

Does this affect you?

Add your gear to cvedb and we'll alert you only when vllm ships something exploited.

Check my exposure →

References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.