SB2026060243 - Inconsistent interpretation of HTTP requests in vLLM

Description

This security bulletin contains information about 1 vulnerability.

1) Inconsistent interpretation of HTTP requests (CVE-ID: CVE-2026-48746)

CWE-ID: CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber

The vulnerability allows a remote attacker to bypass authentication and use the API without providing a valid API key.

The vulnerability exists due to inconsistent interpretation of HTTP requests in OpenAI API AuthenticationMiddleware when processing requests with a crafted Host header that alters the reconstructed URL path. A remote attacker can send a specially crafted request with invalid characters in the Host header to bypass authentication and use the API without providing a valid API key.

Only instances that use an API key for the OpenAI API and are exposed to attackers are vulnerable. Instances behind an RFC-conforming web server such as nginx are not affected.

Remediation

Install update from vendor's website.

References

• https://github.com/vllm-project/vllm/security/advisories/GHSA-94f4-hr76-p5j6
• https://github.com/vllm-project/vllm/pull/43426