CVE-2025-59425

vLLM vulnerable to timing attack at bearer auth

Published Oct 7, 2025 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed

Description

vLLM is an inference and serving engine for large language models (LLMs). Before version 0.11.0rc2, the API key support in vLLM performs validation using a method that was vulnerable to a timing attack. API key validation uses a string comparison that takes longer the more characters the provided API key gets correct. Data analysis across many attempts could allow an attacker to determine when it finds the next correct character in the key sequence. Deployments relying on vLLM's built-in API key validation are vulnerable to authentication bypass using this technique. Version 0.11.0rc2 fixes the issue.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

vllm-project

vllm

affected

Version	Status	Constraints
`< 0.11.0rc2`	affected	—

Configuration 1 [-]

OR	cpe:2.3:a:vllm:vllm::::::::
	cpe:2.3:a:vllm:vllm:0.11.0:rc1::::::

No data.

Vendor	Product	Versions
Vllm-project	Vllm	—

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

Source	ID	Title
Github GHSA	GHSA-wr9h-g72x-mwhm	vLLM is vulnerable to timing attack at bearer auth

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact None

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.566% probability within 30 days)

Exploitation none

Automatable yes

Technical Impact partial

References

Link	Providers
https://github.com/vllm-project/vllm/blob/4b946d693e0af15740e9ca9c0e059d5f333b1083/vllm/entrypoints/openai/api_server.py#L1270-L1274
https://github.com/vllm-project/vllm/commit/ee10d7e6ff5875386c7f136ce8b5f525c8fcef48
https://github.com/vllm-project/vllm/releases/tag/v0.11.0
https://github.com/vllm-project/vllm/security/advisories/GHSA-wr9h-g72x-mwhm
https://nvd.nist.gov/vuln/detail/CVE-2025-59425
https://www.cve.org/CVERecord?id=CVE-2025-59425

History

Oct 16, 2025 6:15 PM First appearance in the feed. Affected versions updated. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Vllm Vllm vllm
CPEs		cpe:2.3:a:vllm:vllm:::::::: cpe:2.3:a:vllm:vllm:0.11.0:rc1::::::
Vendors & Products		Vllm Vllm vllm

Oct 8, 2025 1:45 PM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Vllm-project Vllm-project vllm
Vendors & Products		Vllm-project Vllm-project vllm

Oct 7, 2025 4:15 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Oct 7, 2025 2:15 PM Description updated. Title updated. Weaknesses updated. Added references View changes

Type	Values Removed	Values Added
Description	A flaw was found in vLLM’s API token authentication logic, where token comparisons were not performed in constant time. This weakness could allow an attacker to exploit timing differences to guess valid tokens and bypass authentication.	vLLM is an inference and serving engine for large language models (LLMs). Before version 0.11.0rc2, the API key support in vLLM performs validation using a method that was vulnerable to a timing attack. API key validation uses a string comparison that takes longer the more characters the provided API key gets correct. Data analysis across many attempts could allow an attacker to determine when it finds the next correct character in the key sequence. Deployments relying on vLLM's built-in API key validation are vulnerable to authentication bypass using this technique. Version 0.11.0rc2 fixes the issue.
Title	vllm: Timing Attack in vLLM API Token Verification Leading to Authentication Bypass	vLLM vulnerable to timing attack at bearer auth
Weaknesses		CWE-385
References		https://github.com/vllm-project/vllm/blob/4b946d693e0af15740e9ca9c0e059d5f333b1083/vllm/entrypoints/openai/api_server.py#L1270-L1274 https://github.com/vllm-project/vllm/commit/ee10d7e6ff5875386c7f136ce8b5f525c8fcef48 https://github.com/vllm-project/vllm/releases/tag/v0.11.0 https://github.com/vllm-project/vllm/security/advisories/GHSA-wr9h-g72x-mwhm

Oct 7, 2025 12:15 PM Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		A flaw was found in vLLM’s API token authentication logic, where token comparisons were not performed in constant time. This weakness could allow an attacker to exploit timing differences to guess valid tokens and bypass authentication.
Title		vllm: Timing Attack in vLLM API Token Verification Leading to Authentication Bypass
Weaknesses		CWE-208
References		https://nvd.nist.gov/vuln/detail/CVE-2025-59425 https://www.cve.org/CVERecord?id=CVE-2025-59425
Metrics	threat_severity `None`	cvssV3_1 `{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}` threat_severity `Important`