CVE-2026-115918
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Memory Exhaustion in vLLM via Jinja Template Injection

Vulnerability report for CVE-2026-115918, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-10-26

Last updated on: 2026-10-26

Assigner: GitHub, Inc.

Description

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.

CVSS Scores

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Meta Information

Published
2026-10-26
Last Modified
2026-10-26
Generated
2026-10-26
AI Q&A
2026-10-26
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
vllm-project vllm >= 0.16.0, < 0.32.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-400 The product does not properly control the allocation and maintenance of a limited resource.
CWE-770 The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

Attack-Flow Graph

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Executive Summary

This vulnerability affects vLLM versions 0.16.0 to 0.32.0. It allows an authenticated attacker to inject a malicious Jinja template via the /v1/responses endpoint. The server fails to enforce the trust_request_chat_template policy, enabling CPU or memory exhaustion attacks through template rendering.

Detection Guidance

Check vLLM version with pip show vllm. If version is between 0.16.0 and 0.32.0, the system is vulnerable. Monitor API logs for /v1/responses endpoint requests containing chat_template_kwargs with user-controlled templates.

Impact Analysis

An attacker could exploit this to cause denial-of-service by consuming excessive CPU or memory resources. This may lead to service degradation or crashes, impacting the availability of the vLLM service.

Mitigation Strategies

Upgrade vLLM to version 0.32.0 or later. If upgrading is not possible, restrict access to the /v1/responses endpoint and review server configurations to ensure trust_request_chat_template is enforced.

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