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CVE-2026-111766

CVE-2026-111766 · markdown-it: Quadratic-time denial of service in inline HTML parsing with html enabled

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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 · EPSS 0.4% · Public exploit · Fix available

Published
Updated

Stack: system · node

Affected products and versions

  • markdown-it

    Versions
    • >= 15.0.0, < 15.0.3: Affected
    • < 14.3.3: Affected

    No fix published

  • node-markdown-it Debian:12

    Versions
    • 22.2.3+dfsg+~12.2.3-2
    • 22.2.3+dfsg+~12.2.3-3
    • 22.2.3+dfsg+~12.2.3-4
    • 22.2.3+dfsg+~12.2.3-5
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-markdown-it Debian:13

    Versions
    • 22.2.3+dfsg+~12.2.3-2
    • 22.2.3+dfsg+~12.2.3-3
    • 22.2.3+dfsg+~12.2.3-4
    • 22.2.3+dfsg+~12.2.3-5
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-markdown-it Debian:14

    Versions
    • 22.2.3+dfsg+~12.2.3-2
    • 22.2.3+dfsg+~12.2.3-3
    • 22.2.3+dfsg+~12.2.3-4
    • 22.2.3+dfsg+~12.2.3-5
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • markdown-it npm

    Affected ranges
    • SEMVER: < 14.3.3

    Update to 14.3.3

  • markdown-it npm

    Affected ranges
    • SEMVER: ≥ 15.0.0, < 15.0.3

    Update to 15.0.3

  • node-markdown-it Ubuntu:22.04:LTS

    Versions
    • 10.0.0+dfsg-2
    • 10.0.0+dfsg-3
    • 10.0.0+dfsg-3.1
    • 10.0.0+dfsg-4
    • 10.0.0+dfsg-5
    • 10.0.0+dfsg-6
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-markdown-it Ubuntu:24.04:LTS

    Versions
    • 22.2.3+dfsg+~12.2.3-2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-markdown-it Ubuntu:26.10

    Versions
    • 22.2.3+dfsg+~12.2.3-4
    • 22.2.3+dfsg+~12.2.3-5
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-markdown-it Ubuntu:26.04:LTS

    Versions
    • 22.2.3+dfsg+~12.2.3-2
    • 22.2.3+dfsg+~12.2.3-4
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

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