What’s Vulnerable › Vulnerabilities

CVE-2026-111758: markdown-it: Quadratic-time rendering of a single multi-line link reference definition with default options (regression since 14.0)

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-20 · updated 2026-10-28
• Weakness: CWE-400

Description

markdown-it is a Markdown parser. From versions 14.1.0 to before 14.3.3, and 15.0.0 to before 15.0.3, a link reference definition whose label or title is never closed is O(n²) with default options. Continuation lines are pulled lazily with str += lineContent in src/rules_block/reference.ts, and the subsequent charCodeAt and slice calls flatten the V8 cons-string, copying everything collected so far; this runs before the rule decides the definition is invalid. No options are required to trigger it. This issue has been patched in versions 14.3.3 and 15.0.3.

Affected products

• markdown-it: from 14.1.0, < 14.3.3; from 15.0.0, < 15.0.3

References

• https://github.com/markdown-it/markdown-it/commit/48fbc465812c440020c663f040ab22deaf8f1eca
• https://github.com/markdown-it/markdown-it/commit/d99f48839d37af6fd8a2617516c43dab90755503
• https://github.com/markdown-it/markdown-it/releases/tag/14.3.3
• https://github.com/markdown-it/markdown-it/releases/tag/15.0.3
• https://github.com/markdown-it/markdown-it/security/advisories/GHSA-gfr2-rv44-r23c
• https://github.com/markdown-it/markdown-it/security/advisories/GHSA-gfr2-rv44-r23c

Get alerted when CVE-2026-111758 or the next vulnerability affects your stack