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CVE-2026-115347GHSA-F32H-38GF-RG5R

Mistune before 3.3.0 Quadratic Denial of Service via parse_link_text

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 3.3.0
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: yes
  • Technical impact: partial

Summary

Mistune, a Python library for parsing Markdown, is affected. A remote attacker can send specially crafted Markdown with many unbalanced square brackets, causing the parser to take excessive time and stall processes for minutes, resulting in denial of service.

Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.

Read the original description

Mistune before 3.3.0 contains an inefficient algorithmic complexity vulnerability in parse_link_text that allows remote attackers to cause denial of service through unbalanced square brackets. Attackers can submit markdown containing long runs of unmatched brackets to mistune.html(), triggering repeated forward scans that stall worker processes for minutes.

Timeline

  1. CVE published
  2. First seen by cve.now
  3. CISA SSVC assessment

    Exploitation: none · Automatable: yes · Technical impact: partial

  4. Record last updated

Affected versions

  • lepture mistune

    fixed in 3.3.0

References 2

GitHub · lepture/mistune

vulncheck.com