vLLM is vulnerable to timing attack at bearer auth
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
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 software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | vllm | < 0.11.0 | 0.11.0 |
References
- https://github.com/vllm-project/vllm/security/advisories/GHSA-wr9h-g72x-mwhm
- https://nvd.nist.gov/vuln/detail/CVE-2025-59425
- https://github.com/vllm-project/vllm/commit/ee10d7e6ff5875386c7f136ce8b5f525c8fcef48
- https://github.com/vllm-project/vllm
- https://github.com/vllm-project/vllm/blob/4b946d693e0af15740e9ca9c0e059d5f333b1083/vllm/entrypoints/openai/api_server.py#L1270-L1274
- https://github.com/vllm-project/vllm/releases/tag/v0.11.0
- https://pypi.org/project/vllm
- https://github.com/advisories/GHSA-wr9h-g72x-mwhm
- https://github.com/pypa/advisory-database/tree/main/vulns/vllm/PYSEC-2026-2026.yaml
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N- Weakness (CWE)
CWE-385- Platform
- Python (PyPI)
- Package
vllm- Disclosed
- 07.10.2025
- Updated
- 11.10.2026 15:17
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2026-2026 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-wr9h-g72x-mwhm - CC BY 4.0
Vulnerability history: vllm
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 94
- First → latest
- 09.2024 10.2026
- Without a fix
- 5
- Exploited in attacks
- 0
Severity breakdown
- Critical 9
- High 23
- Medium 47
- Low 4
- Unrated 11
Disclosures per year
- 2024: 2
- 2025: 30
- 2026: 62
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vLLM is vulnerable to timing attack at bearer auth this entry
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