PYSEC-2026-2026

vLLM is vulnerable to timing attack at bearer auth

Description

### Summary The API key support in vLLM performed validation using a method that was vulnerable to a timing attack. This could potentially allow an attacker to discover a valid API key using an approach more efficient than brute force. ### Details https://github.com/vllm-project/vllm/blob/4b946d693e0af15740e9ca9c0e059d5f333b1083/vllm/entrypoints/openai/api_server.py#L1270-L1274 API key validation used a string comparison that will take longer the more characters the provided API key gets correct. Data analysis across many attempts can allow an attacker to determine when it finds the next correct character in the key sequence. ### Impact Deployments relying on vLLM's built-in API key validation are vulnerable to authentication bypass using this technique.

Affected packages

References

• https://github.com/vllm-project/vllm/security/advisories/GHSA-wr9h-g72x-mwhm WEB
• https://nvd.nist.gov/vuln/detail/CVE-2025-59425 ADVISORY
• https://github.com/vllm-project/vllm/commit/ee10d7e6ff5875386c7f136ce8b5f525c8fcef48 WEB
• https://github.com/vllm-project/vllm PACKAGE
• https://github.com/vllm-project/vllm/blob/4b946d693e0af15740e9ca9c0e059d5f333b1083/vllm/entrypoints/openai/api_server.py#L1270-L1274 WEB
• https://github.com/vllm-project/vllm/releases/tag/v0.11.0 WEB
• https://pypi.org/project/vllm PACKAGE
• https://github.com/advisories/GHSA-wr9h-g72x-mwhm ADVISORY

Sources