CVE-2026-67987

Denial‑of‑Service via Polynomial‑Time Regex in ruby_llm <think> Tag Parsing

Published Sep 29, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
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

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Crmne
Crmne ruby Llm
Vendors & Products Crmne
Crmne ruby Llm
Type Values Removed Values Added
Title Denial‑of‑Service via Polynomial‑Time Regex in ruby_llm <think> Tag Parsing
Type Values Removed Values Added
Title Ruby LLM Regular Expression Denial‑of‑Service in Think‑Tag Parsing
Weaknesses CWE-20
CWE-770
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-1333
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Type Values Removed Values Added
Title Ruby LLM Regular Expression Denial‑of‑Service in Think‑Tag Parsing
Weaknesses CWE-20
CWE-770
Type Values Removed Values Added
Description 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
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
mitre
Published
Updated
Oct 1, 2026, 3:22 PM
Reserved
Jul 30, 2026, 12:00 AM
Status
Deferred
Published
Sep 29, 2026, 8:17 PM
Modified
Oct 1, 2026, 4:17 PM