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.
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Affected Vendors & Products
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Fixes
Solution
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Workaround
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References
History
Tue, 20 Oct 2026 00:30:00 +0000
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| Weaknesses | CWE-1333 | |
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threat_severity
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threat_severity
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Mon, 19 Oct 2026 21:45:00 +0000
| Type | Values Removed | Values Added |
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Markdown-it
Markdown-it markdown-it |
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| Vendors & Products |
Markdown-it
Markdown-it markdown-it |
Mon, 19 Oct 2026 20:00:00 +0000
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| Description | 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. | |
| Title | markdown-it: Quadratic-time denial of service in inline HTML parsing with html enabled | |
| Weaknesses | CWE-400 CWE-407 |
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| Metrics |
cvssV3_1
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Projects
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-10-19T19:47:46.488Z
Reserved: 2026-10-16T17:52:09.082Z
Link: CVE-2026-111766
No data.
Status : Awaiting Analysis
Published: 2026-10-19T20:17:52.247
Modified: 2026-10-19T21:13:39.973
Link: CVE-2026-111766
OpenCVE Enrichment
Updated: 2026-10-19T21:45:04Z