---
id: CVE-2026-67987
title: >-
  crmne/ruby_llm at commit fa6f279847d6d7027814539d9c0dfc3bbdfd2a83 contains
  polynomial-time regular expression denial-of-service conditions in think-tag
  response parsing on Ruby 3.1.x
summary: >-
  crmne/ruby_llm at commit fa6f279847d6d7027814539d9c0dfc3bbdfd2a83 contains
  polynomial-time regular expression denial-of-service conditions in think-tag
  response parsing on Ruby 3.1.x. A malicious or anomalous model response
  containing ma…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-1333
published: '2026-09-29'
updated: '2026-10-01'
sourceUpdated: '2026-10-01T16:17:47.723'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-67987'
references:
  - url: 'https://github.com/crmne/ruby_llm'
    label: cve@mitre.org
  - url: >-
      https://github.com/crmne/ruby_llm/blob/fa6f279847d6d7027814539d9c0dfc3bbdfd2a83/lib/ruby_llm/protocols/chat_completions/chat.rb#L355-L356
    label: cve@mitre.org
  - url: >-
      https://github.com/crmne/ruby_llm/commit/5e88411f171721b381853fa77d254e266dcf6ad8
    label: cve@mitre.org
tags:
  - nvd
  - cve.org
epss: 0.00432
epssPercentile: 0.3724
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-01T15:21:55.298371Z'
ingestedAt: '2026-09-29T20:46:06.446Z'
---

## Overview

crmne/ruby_llm at commit fa6f279847d6d7027814539d9c0dfc3bbdfd2a83 contains polynomial-time regular expression denial-of-service conditions in think-tag response parsing on Ruby 3.1.x. A malicious or anomalous model response containing many unterminated <think> tags can cause excessive CPU consumption in two consecutive regular expressions and delay chat-completion processing

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.