CVE-2026-71478
league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a javascript: URL that browsers discard before parsing the scheme, causing the browser to still execute the script even when the unsafe-link filter is enabled. This issue is fixed in 2.9.0.
Scoring
- Severity
- MEDIUM
- CVSS base score
- 6.1
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- EPSS probability
- 0.20%
- CWE
- CWE-79, CWE-86, CWE-692
- Published
- 2026-08-06
- Last modified
- 2026-08-07
Affected products
- thephpleague commonmark