#VU124867 Improper input validation in vLLM - CVE-2026-34756
Published: April 4, 2026
Vulnerability identifier: #VU124867
Vulnerability risk: Low
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-34756
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
vLLM
vLLM
Software vendor:
vLLM
vLLM
Description
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to improper input validation in the OpenAI-compatible API server request handling for the n parameter when processing HTTP requests. A remote user can send a single HTTP request with an excessively large n value to cause a denial of service.
This issue affects the ChatCompletionRequest and CompletionRequest models and can block the Python asyncio event loop while triggering out-of-memory crashes by allocating large numbers of request object copies before scheduling.
Remediation
Install security update from vendor's website.