CVE-2026-111766markdown-it: Quadratic-time denial of service in inline HTML parsing with html enabled
Updated under an hour ago ()
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It affects markdown-it. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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markdown-it is a Markdown parser. Prior to 14.3.3 and 15.0.3, when the html option or commonmark preset is enabled and the constructs occur inside a paragraph, attacker-controlled Markdown containing repeated unterminated inline HTML comments, processing instructions, declarations, or CDATA sections reaches src/rules_inline/html_inline.ts. Its HTML_TAG_RE match searches the remaining suffix for the appropriate terminator; when no terminator is present, parsing advances to the next opener and repeats the match over overlapping input, causing quadratic processing and denial of service through event-loop blocking or an unresponsive browser main thread. HTML blocks and the default HTML-disabled configuration are not affected by these payloads. This issue is fixed in versions 14.3.3 and 15.0.3.
- CVSS
- 3.7 LOW (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
- Weakness (CWE)
- CWE-400, CWE-407
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Awaiting Analysis
- Record last updated
- Oct 19, 2026
- First seen by InfoSec Signals
- Oct 19, 2026
Affected products
markdown-it markdown-it markdown_it:markdown_it (from the name) | from 15.0.0, < 15.0.3; before 14.3.3 | CNA record |
References
- https://github.com/markdown-it/markdown-it/security/advisories/GHSA-vfgh-jcmw-g37qx-refsource-confirm
- https://github.com/markdown-it/markdown-it/commit/928bc8c11ded60181c0e7fc5aa954eec582e8e79x-refsource-misc
- https://github.com/markdown-it/markdown-it/commit/d99f48839d37af6fd8a2617516c43dab90755503x-refsource-misc
- https://github.com/markdown-it/markdown-it/releases/tag/14.3.3x-refsource-misc
- https://github.com/markdown-it/markdown-it/releases/tag/15.0.3x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.