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  4. CVE 2026 86428 commonmark 150 before 2100 denial of service via
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Back to active CVEs
High · CVSS 8.7CVE-2026-86428GHSA-8RR7-CVQ3-GMFH

commonmark 1.5.0 before 2.10.0 Denial of Service via AttributesCVE-2026-86428

Answer in brief

CVE-2026-86428 records a High severity (CVSS 8.7) vulnerability in commonmark 1.5.0 before 2.10.0 Denial of Service via Attributes. The current sources do not mark it as known exploited. The current feed maps league/commonmark (composer), thephpleague/commonmark (generic), league/commonmark (packagist). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

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

Published Sep 7, 2026Updated Oct 8, 2026Source checked Oct 25, 2026First seen by HOL Sep 1, 2026Material review Oct 8, 2026
Upstream Advisory

Record context

Vulnerability class
Vulnerability
EPSS
Not reported
CWE IDs
CWE-407, CWE-1050
Source
CVE List V5
Source checked
Oct 25, 2026
References
6 linked sources
Open source record

Key facts

Risk
High · CVSS 8.7
Exploitation
Not marked as known exploited
Affected software
4 mapped packages or products
Fix availability
Available

Why this deserves its current priority

CVSS is 8.7. 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 league/commonmark (composer), thephpleague/commonmark (generic), league/commonmark (packagist). Check affected ranges and fixed versions before updating.

Affected products and reported versions
ProductAffected versionsFixed versions
cpe:2.3:a:thephpleague:commonmark:*:*:*:*:*:*:*:*Not reportedNot reported
Mapped affected packages and fixed versions
PackageAffected rangeFixed version
league/commonmarkcomposer>=1.5.0,<2.10.02.10.0
thephpleague/commonmarkgeneric>=1.5.0 <2.10.02.10.0
league/commonmarkpackagist>=1.5.0 <2.10.02.10.0

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for league/commonmark, thephpleague/commonmark, league/commonmark.
  2. 2Review the reported fix. Update league/commonmark to 2.10.0; thephpleague/commonmark to 2.10.0; league/commonmark to 2.10.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Sep 7, 2026

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

  2. Source modified

    Oct 8, 2026

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

  3. First seen by HOL

    Sep 1, 2026

Sources and claim methodology

  • GitHub security advisorygithub.com
  • Source referencevulncheck.com
  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
Upstream source description

commonmark versions from 1.5.0 before 2.10.0 contain a denial of service vulnerability in the AttributesExtension when processing distinctly-named attributes. Attackers can submit Markdown with numerous distinct attribute names to cause quadratic-time attribute merging and filtering, consuming disproportionate CPU resources and preventing legitimate requests from completing.

Quoted source text, attributed separately from HOL analysis.