CVE-2026-111758
markdown-it: Quadratic-time rendering of a single multi-line link reference definition with default options (regression since 14.0)
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-400 CWE-407 |
| Vendor | markdown-it |
| Product | markdown-it |
| Published | Oct 20, 2026 |
Stay Ahead of the Next One
Get instant alerts for markdown-it markdown-it
Be the first to know when new high vulnerabilities affecting markdown-it markdown-it are published — delivered to Slack, Telegram or Discord.
Get Free Alerts →
Free · No credit card · 60 sec setup
CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
markdown-it / markdown-it
>= 14.1.0, < 14.3.3 >= 15.0.0, < 15.0.3
References
github.com: https://github.com/markdown-it/markdown-it/security/advisories/GHSA-gfr2-rv44-r23c github.com: https://github.com/markdown-it/markdown-it/commit/48fbc465812c440020c663f040ab22deaf8f1eca github.com: https://github.com/markdown-it/markdown-it/commit/d99f48839d37af6fd8a2617516c43dab90755503 github.com: https://github.com/markdown-it/markdown-it/releases/tag/14.3.3 github.com: https://github.com/markdown-it/markdown-it/releases/tag/15.0.3