CVE-2025-46734 Details
Description
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.
A cross-site scripting (XSS) vulnerability has been identified in the Attributes extension of the league/commonmark library, affecting versions 1.5.0 prior to 2.7.0. This vulnerability allows remote attackers to inject malicious JavaScript into HTML. The issue arises because the Attributes extension enables users to add arbitrary HTML attributes to elements using Markdown syntax, which can be exploited to execute JavaScript. Although the league/commonmark library offers some configuration options to mitigate XSS attacks, these protections can be bypassed when the Attributes extension is active.
Upgrade to league/commonmark version 2.7.0 or later, where this vulnerability is fixed. If upgrading is not possible, consider disabling the Attributes extension for untrusted users or filtering the rendered HTML with a library like HTMLPurifier.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed May 5, 2025CISA-ADP
Assessed May 6, 2025References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/thephpleague/commonmark/commit/f0d626cf05ad3e99e6db26ebcb9091b6cd1cd89b | [email protected] | Source CodeVendor |
| https://github.com/thephpleague/commonmark/security/advisories/GHSA-3527-qv2q-pfvx | [email protected] | AdvisoryRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-79 | Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| league/commonmark | All versions |
CPE
Remediation
| |
Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| May 5, 2025 | New CVE Received | [email protected] |