CVE-2026-34756

CVE-2026-34756 affects vLLM OpenAI-compatible API server prior to 0.19.0. The root cause is missing upper-bound validation on the n parameter in ChatCompletionRequest/CompletionRequest, allowing an unauthenticated attacker to send an astronomically large n value that causes the asyncio event loop...

CVE-2026-34756 vLLM Affected by Unauthenticated OOM Denial of Service via Unbounded `n` Parameter in OpenAI API Server

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 CompletionReques...