vllm-project vLLM up to 0.31.x Chat Template /v1/responses ChatParams.get_apply_chat_template_kwargs chat_template memory allocation

Summaryinfo

A vulnerability was found in vllm-project vLLM up to 0.31.x and classified as problematic. Affected by this issue is the function ChatParams.get_apply_chat_template_kwargs of the file /v1/responses of the component Chat Template. The manipulation of the argument chat_template results in memory allocation. This vulnerability is known as CVE-2026-115918. It is possible to launch the attack remotely. No exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in vllm-project vLLM up to 0.31.x. It has been classified as problematic. Affected is the function ChatParams.get_apply_chat_template_kwargs of the file /v1/responses of the component Chat Template. The manipulation of the argument chat_template with an unknown input leads to a memory allocation vulnerability. CWE is classifying the issue as CWE-789. The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated. This is going to have an impact on availability. CVE summarizes:

vLLM is an inference and serving engine for large language models. From 0.16.0 until 0.32.0, the /v1/responses endpoint allows an authenticated caller to place an attacker-controlled template in chat_template_kwargs[chat_template] when no server template is configured. ChatParams.get_apply_chat_template_kwargs() preserves that value without enforcing trust_request_chat_template, so the request can bypass the intended trust policy and cause CPU or memory exhaustion through Jinja rendering. This issue is fixed in version 0.32.0.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-115918 since 10/23/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. Technical details are known, but there is no available exploit.

Upgrading to version 0.32.0 eliminates this vulnerability.

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Productinfo

Type

• Project Management Software

Vendor

• vllm-project

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
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21
• 0.22
• 0.23
• 0.24
• 0.25
• 0.26
• 0.27
• 0.28
• 0.29
• 0.30
• 0.31

Website

• Product: https://github.com/vllm-project/vllm/

CPE 2.3info

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CPE 2.2info

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