league/commonmark is a PHP Markdown parser. A cross-site scripting (XSS) vulnerability in the Attributes extension of the league/commonmark library (versions 1.5.0 through 2.6.x) allows remote attackers to insert malicious JavaScript calls into HTML. The league/commonmark library provides configuration options such as `html_input: 'strip'` and `allow_unsafe_links: false` to mitigate cross-site scripting (XSS) attacks by stripping raw HTML and disallowing unsafe links. However, when the Attributes Extension is enabled, it introduces a way for users to inject arbitrary HTML attributes into elements via Markdown syntax using curly braces. Version 2.7.0 contains three changes to prevent this XSS attack vector: All attributes starting with `on` are considered unsafe and blocked by default; support for an explicit allowlist of allowed HTML attributes; and manually-added `href` and `src` attributes now respect the existing `allow_unsafe_links` configuration option. If upgrading is not feasible, please consider disabling the `AttributesExtension` for untrusted users and/or filtering the rendered HTML through a library like HTMLPurifier.
References
Configurations
No configuration.
History
05 May 2025, 20:15
Type | Values Removed | Values Added |
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New CVE |
Information
Published : 2025-05-05 20:15
Updated : 2025-05-05 20:54
NVD link : CVE-2025-46734
Mitre link : CVE-2025-46734
CVE.ORG link : CVE-2025-46734
JSON object : View
Products Affected
No product.
CWE
CWE-79
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')