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...

GHSA-3MWP-WVH9-7528 vLLM: Unauthenticated OOM Denial of Service via Unbounded `n` Parameter in OpenAI API Server

Summary 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...

Server-Side Request Forgery (SSRF)

vllm is vulnerable to a Server-Side Request Forgery SSRF. The vulnerability is due to inconsistent URL parsing and hostname validation in the MediaConnector class when processing user-supplied media URLs, which allows an attacker to bypass host restrictions and coerce the vLLM server into making...

CVE-2025-48943 vLLM allows clients to crash the openai server with invalid regex

vLLM is an inference and serving engine for large language models LLMs. Version 0.8.0 up to but excluding 0.9.0 have a Denial of Service ReDoS that causes the vLLM server to crash if an invalid regex was provided while using structured output. This vulnerability is similar to...

CVE-2025-48942 vLLM DOS: Remotely kill vllm over http with invalid JSON schema

vLLM is an inference and serving engine for large language models LLMs. In versions 0.8.0 up to but excluding 0.9.0, hitting the /v1/completions API with a invalid jsonschema as a Guided Param kills the vllm server. This vulnerability is similar GHSA-9hcf-v7m4-6m2j/CVE-2025-48943, but for regex...

GHSA-9HCF-V7M4-6M2J vLLM allows clients to crash the openai server with invalid regex

Impact A denial of service bug caused the vLLM server to crash if an invalid regex was provided while using structured output. This vulnerability is similar to GHSA-6qc9-v4r8-22xg, but for regex instead of a JSON schema. Issue with more details: https://github.com/vllm-project/vllm/issues/17313...

GHSA-6QC9-V4R8-22XG vLLM DOS: Remotely kill vllm over http with invalid JSON schema

Summary Hitting the /v1/completions API with a invalid jsonschema as a Guided Param will kill the vllm server Details The following API call venv derekh@ip-172-31-15-108 $ curl -s http://localhost:8000/v1/completions -H "Content-Type: application/json" -d '"model":...