CVE-2026-115911

MEDIUM
MEDIUM Priority: 0.02 BB Relevance: 63/100
Published: 2026-10-26 Modified: 2026-10-28 First seen: 2026-10-29 Status: active

Attack Surface

Network Low Complexity No Interaction

CVSS Vector Breakdown

AV: Network
AC: Low
PR: Low
UI: None
S: Unchanged
C: None
I: None
A: High

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.

Weakness Classification (3)

Affected Software (1)

VendorProductVersion
vllm vllm 0.19.0 – 0.32.0

Bug Bounty Relevance

63 / 100
✓ Network accessible
✓ Low complexity
✓ No user interaction

CVSS Score

6.5 / 10.0 v3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploitation Probability

0.31%
Raw Score 0.003120
Percentile 24.0%
Date 2026-10-29

EPSS Trend

2026-10-29
0.00312
2026-10-28
0.00305

Intelligence Sources

mitre ref →
nvd ref →