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Back to active CVEs
Low · CVSS 3.7CVE-2026-111766

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

Answer in brief

CVE-2026-111766 records a Low severity (CVSS 3.7) vulnerability in markdown-it: Quadratic-time denial of service in inline HTML parsing with html enabled. The current sources do not mark it as known exploited. The current feed maps markdown-it/markdown-it (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 19, 2026Updated Oct 19, 2026Source checked Oct 19, 2026First seen by HOL Oct 19, 2026Material review Oct 19, 2026
Upstream Advisory

Key facts

Risk
Low · CVSS 3.7
Exploitation
Not marked as known exploited
Affected software
1 mapped package or product
Fix availability
Available

Why this deserves its current priority

CVSS is 3.7. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps markdown-it/markdown-it (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
PackageAffected rangeFixed version
markdown-it/markdown-itgeneric>=15.0.0 <15.0.3 || <14.3.314.3.3, 15.0.3

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for markdown-it/markdown-it.
  2. 2Review the reported fix. Update markdown-it/markdown-it to 14.3.3 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Oct 19, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Oct 19, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Oct 19, 2026

Sources and claim methodology

  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
Upstream source 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.

Quoted source text, attributed separately from HOL analysis.

Related CVEs

  • Cpanel::JSON::XS versions from 4.51 before 4.80 for Perl allow quadratic CPU use by revalidating the remaining buffer per value in incr_parseAlso CWE-407
  • DiffSK configobj __init__.py _sectionmarker redosAlso CWE-400
  • Grav before 1.7.53.5 and 2.2.2 Image Pixel Limit Bypass Denial of ServiceAlso CWE-400

Record context

Vulnerability class
Vulnerability
EPSS
Not reported
CWE IDs
CWE-400, CWE-407
Source
CVE List V5
Source checked
Oct 19, 2026
References
5 linked sources
Open source record