Disclosure 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.
Source-reported weakness categories
CWE-407
Source-specific records & product guidance
Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.
NIST National Vulnerability Database · NVD-CVE-2026-86428
Open original source · Updated Oct 08, 2026
Only CPE matches marked vulnerable=true are indexed. AND/OR platform conditions must be checked in the original NVD record.
| Vendor | Product / association | Version / bounds |
|---|---|---|
| thephpleague | commonmark | * {"versionStartIncluding":"1.5.0","versionEndExcluding":"2.10.0"} |
Original records & references
- NIST NVD record
- CVE Program record
- github.com — Mitigation, Vendor Advisory
- www.vulncheck.com — Third Party Advisory
PUBLISHED 2026-09-07T09:20:42-04:00
MODIFIED 2026-10-08T12:17:56-04:00
INGESTED 2026-10-10T20:50:36-04:00