CVE-2026-71478
league/commonmark: AttributesExtension href/src unsafe-link filter bypass via embedded control bytes
CVSS Score
6.1
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-79 CWE-86 CWE-692 |
| Vendor | thephpleague |
| Product | commonmark |
| Published | Aug 6, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None
Affected Versions
thephpleague / commonmark
>= 1.5.0, <= 2.8.3