# CVE-2026-30838: php-league-commonmark: league/commonmark is a PHP Markdown parser

CVE-2026-30838 is fixed in php-league-commonmark on 1 platform, first by DEBIAN-CVE-2026-30838, released March 7, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-30838
- Priority: Routine
- CVSS: 6.1 (medium)
- EPSS: 0.0025
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 7, 2026

## Description

league/commonmark is a PHP Markdown parser. Prior to version 2.8.1, the DisallowedRawHtml extension can be bypassed by inserting a newline, tab, or other ASCII whitespace character between a disallowed HTML tag name and the closing >. For example, <script\n> would pass through unfiltered and be rendered as a valid HTML tag by browsers. This is a cross-site scripting (XSS) vector for any application that relies on this extension to sanitize untrusted user input. All applications using the DisallowedRawHtml extension to process untrusted markdown are affected. Applications that use a dedicated HTML sanitizer (such as HTML Purifier) on the rendered output are not affected. This issue has been patched in version 2.8.1.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | php-league-commonmark Debian 12.15 (bookworm) | 2.3.9-1+deb12u1 | [DEBIAN-CVE-2026-30838](https://patchblox.com/security/data/fix/linux/debian-cve-2026-30838.md) | Mar 7, 2026 |
| Linux | php-league-commonmark Debian 13.5 (trixie) | 2.7.0-1+deb13u1 | [DEBIAN-CVE-2026-30838](https://patchblox.com/security/data/fix/linux/debian-cve-2026-30838.md) | Mar 7, 2026 |
| Linux | php-league-commonmark Debian 14 | 2.8.1-1 | [DEBIAN-CVE-2026-30838](https://patchblox.com/security/data/fix/linux/debian-cve-2026-30838.md) | Mar 7, 2026 |
| Linux | php-league-commonmark Ubuntu 20.04 LTS (focal) | 1.3.1-1ubuntu2+esm1 | [php-league-commonmark 1.3.1-1ubuntu2+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-php-league-commonmark-1.3.1-1ubuntu2-esm1.md) | Mar 24, 2026 |
| Linux | php-league-commonmark Ubuntu 22.04.1 LTS (jammy) | 1.6.7-1ubuntu0.1~esm1 | [php-league-commonmark 1.6.7-1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-php-league-commonmark-1.6.7-1ubuntu0.1-esm1.md) | Mar 24, 2026 |
| Linux | php-league-commonmark Ubuntu 24.04.5 LTS (noble) | 2.4.2-2ubuntu0.1~esm1 | [php-league-commonmark 2.4.2-2ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-php-league-commonmark-2.4.2-2ubuntu0.1-esm1.md) | Mar 24, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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