vLLM is an inference and serving engine for large language models. From 0.19.0 until 0.32.0, authenticated callers can supply a request chat template when no server-side --chat-template is configured, or a malicious model repository can provide a template that is compiled and rendered by tokenizer.apply_chat_template() without a wall-clock timeout, output-size limit, or iteration bound. Rendering runs in a ThreadPoolExecutor with one worker by default, so a nonterminating render can block /v1/responses and other chat-template users after the request ends, while an output-expanding render can exhaust server memory. Harmony models are not affected because they do not use this Jinja path. This issue is fixed in version 0.32.0.
History

Fri, 30 Oct 2026 15:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 28 Oct 2026 15:45:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:vllm:vllm:*:*:*:*:*:*:*:*

Tue, 27 Oct 2026 12:30:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Mon, 26 Oct 2026 18:45:00 +0000

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

Mon, 26 Oct 2026 17:00:00 +0000

Type Values Removed Values Added
Description vLLM is an inference and serving engine for large language models. From 0.19.0 until 0.32.0, authenticated callers can supply a request chat template when no server-side --chat-template is configured, or a malicious model repository can provide a template that is compiled and rendered by tokenizer.apply_chat_template() without a wall-clock timeout, output-size limit, or iteration bound. Rendering runs in a ThreadPoolExecutor with one worker by default, so a nonterminating render can block /v1/responses and other chat-template users after the request ends, while an output-expanding render can exhaust server memory. Harmony models are not affected because they do not use this Jinja path. This issue is fixed in version 0.32.0.
Title vLLM: DoS via unbounded chat_template Jinja2 rendering exhausts the renderer thread pool
Weaknesses CWE-400
CWE-770
CWE-834
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-10-26T16:47:59.377Z

Updated: 2026-10-30T14:20:51.484Z

Reserved: 2026-10-23T20:21:45.107Z

Link: CVE-2026-115911

cve-icon Vulnrichment

Updated: 2026-10-30T14:20:46.051Z

cve-icon NVD

Status : Analyzed

Published: 2026-10-26T17:17:18.753

Modified: 2026-10-30T15:16:45.860

Link: CVE-2026-115911

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-10-26T16:47:59Z

Links: CVE-2026-115911 - Bugzilla