Vulnerability · Published Oct 20, 2026 · Assigned by GitHub_M
CVE-2026-111758markdown-it: Quadratic-time rendering of a single multi-line link reference definition with default options (regression since 14.0)
High 7.5
In plain English
A high-severity uncontrolled resource consumption in markdown-it from markdown-it. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 46% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu:22.04:LTS | node-markdown-it | no fix listed | UBUNTU-CVE-2026-111758 |
| Ubuntu:24.04:LTS | node-markdown-it | no fix listed | UBUNTU-CVE-2026-111758 |
| Ubuntu:26.04:LTS | node-markdown-it | no fix listed | UBUNTU-CVE-2026-111758 |
| Ubuntu:26.10 | node-markdown-it | no fix listed | UBUNTU-CVE-2026-111758 |
| npm | markdown-it | 14.3.3 | GHSA-gfr2-rv44-r23c |
| npm | markdown-it | 15.0.3 | GHSA-gfr2-rv44-r23c |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| markdown-it | markdown-it | >= 14.1.0, < 14.3.3>= 15.0.0, < 15.0.3 |
Weakness: CWE-400, CWE-407 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://github.com/markdown-it/markdown-it/security/advisories/GHSA-gfr2-rv44-r23c x_refsource_CONFIRM
- https://github.com/markdown-it/markdown-it/commit/48fbc465812c440020c663f040ab22deaf8f1eca x_refsource_MISC
- https://github.com/markdown-it/markdown-it/commit/d99f48839d37af6fd8a2617516c43dab90755503 x_refsource_MISC
- https://github.com/markdown-it/markdown-it/releases/tag/14.3.3 x_refsource_MISC
- https://github.com/markdown-it/markdown-it/releases/tag/15.0.3 x_refsource_MISC