Description
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.
Severity (CVSS)
| Base score | 6.1 |
|---|---|
| Severity | Medium |
| Version | CVSS 3.1 |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| Provided by | CNA |
Weaknesses
- CWE-79 — CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- CWE-86 — CWE-86: Improper Neutralization of Invalid Characters in Identifiers in Web Pages
- CWE-692 — CWE-692: Incomplete Denylist to Cross-Site Scripting
Affected products
| Vendor | Product | Versions |
|---|---|---|
| thephpleague | commonmark | >= 1.5.0, <= 2.8.3 |
References
- https://github.com/thephpleague/commonmark/security/advisories/GHSA-29pj-957v-52mc (x_refsource_CONFIRM)
- https://github.com/thephpleague/commonmark/commit/493a5aa7d65754b73846006eaff9c2c4431a8e2c (x_refsource_MISC)
- https://github.com/thephpleague/commonmark/releases/tag/2.9.0 (x_refsource_MISC)
Generated from the official CVE List on 07 Aug 2026 07:02 UTC.