All vulnerabilities
CVE-2026-115348GHSA-x2gr-6qf2-fc9x

Mistune before 3.3.0 Quadratic-Time DoS 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)0.36%Chance of exploitation activity in the next 30 days, higher than 28% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in3.3.0Fixed versionCVE List
Published22 Oct 2026Updated 23 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 from 3.0.0 before 3.3.0 contains an algorithmic complexity vulnerability in the inline link parser's parse_link_text function that allows unauthenticated attackers to exhaust CPU with unbalanced brackets. Attackers can submit Markdown containing many unbalanced '[' or '![' characters, forcing repeated unbounded forward scans and tying up worker processes for minutes.

Text from CVE List

Affected versions 2

  • mistuneaffected: 3.0.0 before 3.3.0CVE List
  • mistuneunaffected: 3.3.0CVE List

References 2