All vulnerabilities
CVE-2026-115347GHSA-f32h-38gf-rg5r

Mistune before 3.3.0 Quadratic Denial of Service via parse_link_text

lepture mistune
Open in ThreatlineRecord JSON
CVSS
8.7High
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.41%Chance of exploitation activity in the next 30 days, higher than 34% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in3.3.0Fixed versionCVE List
Published22 Oct 2026Updated 22 Oct 2026CVE List

What fixes it

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

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.

Text from CVE List

Affected versions 2

  • mistuneaffected: all versions before 3.3.0CVE List
  • mistuneunaffected: 3.3.0CVE List

References 2