vLLM up to 0.11.0 Request Parameter /v1/chat/completions chat_template_kwargs allocation of resources

Summaryinfo

A vulnerability marked as critical has been reported in vLLM up to 0.11.0. Affected by this vulnerability is the function chat_template_kwargs of the file /v1/chat/completions of the component Request Parameter Handler. The manipulation leads to allocation of resources. This vulnerability is listed as CVE-2025-62426. The attack may be initiated remotely. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in vLLM up to 0.11.0 and classified as critical. This issue affects the function chat_template_kwargs of the file /v1/chat/completions of the component Request Parameter Handler. The manipulation with an unknown input leads to a allocation of resources vulnerability. Using CWE to declare the problem leads to CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. Impacted is availability. The summary by CVE is:

vLLM is an inference and serving engine for large language models (LLMs). From version 0.5.5 to before 0.11.1, the /v1/chat/completions and /tokenize endpoints allow a chat_template_kwargs request parameter that is used in the code before it is properly validated against the chat template. With the right chat_template_kwargs parameters, it is possible to block processing of the API server for long periods of time, delaying all other requests. This issue has been patched in version 0.11.1.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2025-62426 since 10/13/2025. The exploitation is known to be easy. The attack may be initiated remotely. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 0.11.1 eliminates this vulnerability.

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Productinfo

Name

• vLLM

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11.0

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

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• 🔒
• 🔒

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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