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AI agent vulnerability · vLLM

CVE-2025-59425: vLLM is vulnerable to timing attack at bearer auth

highCVSS 3.1 7.5GHSA-wr9h-g72x-mwhm

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.

Published Oct 7, 2025 · Updated Jul 17, 2026

Affected packages

vllm

Ecosystem
PyPI
Affected
< 0.11.0
Fixed in
0.11.0
Check
pip show vllm

Advisory details

From the GitHub Advisory Database (CC BY 4.0).

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.

Credited to NiuBlibing, russellb.

References

How this page is made: the data panel comes from the GitHub Advisory Database, CISA’s KEV catalog, the NVD and FIRST EPSS, and updates twice a day. No analysis has been written for this entry yet. Methodology

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