CVE-2026-86428

Summary

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.

Affected Software

VendorProductVersion RangeStatus
thephpleaguecommonmark1.5.0 < 2.10.0affected
thephpleaguecommonmark2.10.0unaffected

Weaknesses

  • CWE-407: Inefficient Algorithmic Complexity

References