p PatchFirst

CVE-2026-30838

CVE-2026-30838 · league/commonmark: DisallowedRawHtml extension bypass via whitespace in HTML tag names

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 5.1 · Medium · EPSS 0.2% · Fix available

Published
Updated

Stack: system · php

Affected products and versions

  • commonmark

    Versions
    • < 2.8.1: Affected

    No fix published

  • php-league-commonmark Debian:12

    Versions
    • 2.3.9-1
    Affected ranges
    • ECOSYSTEM: < 2.3.9-1+deb12u1

    Update to 2.3.9-1+deb12u1

  • php-league-commonmark Debian:13

    Versions
    • 2.7.0-1
    Affected ranges
    • ECOSYSTEM: < 2.7.0-1+deb13u1

    Update to 2.7.0-1+deb13u1

  • php-league-commonmark Debian:14

    Versions
    • 2.7.0-1
    • 2.7.1-1
    • 2.7.1-2
    • 2.8.0-1
    Affected ranges
    • ECOSYSTEM: < 2.8.1-1

    Update to 2.8.1-1

  • league/commonmark Packagist

    Versions
    • 2.0.0
    • 2.0.1
    • 2.0.2
    • 2.0.3
    • 2.0.4
    • 2.1.0
    • 2.1.1
    • 2.1.2
    • 2.1.3
    • 2.2.0
    • 2.2.1
    • 2.2.2
    • 2.2.3
    • 2.2.4
    • 2.2.5
    • 2.3.0
    • 2.3.1
    • 2.3.2
    • 2.3.3
    • 2.3.4
    • 2.3.5
    • 2.3.6
    • 2.3.7
    • 2.3.8
    • 2.3.9
    • 2.4.0
    • 2.4.1
    • 2.4.2
    • 2.4.3
    • 2.4.4
    • 2.5.0
    • 2.5.1
    • 2.5.2
    • 2.5.3
    • 2.6.0
    • 2.6.1
    • 2.6.2
    • 2.7.0
    • 2.7.1
    • 2.8.0
    Affected ranges
    • ECOSYSTEM: ≥ 2.0.0, < 2.8.1

    Update to 2.8.1

  • php-league-commonmark Ubuntu:Pro:20.04:LTS

    Versions
    • 1.1.2-1
    • 1.2.0-1
    • 1.3.0-1
    • 1.3.1-1
    • 1.3.1-1ubuntu2
    Affected ranges
    • ECOSYSTEM: < 1.3.1-1ubuntu2+esm1

    Update to 1.3.1-1ubuntu2+esm1

  • php-league-commonmark Ubuntu:Pro:22.04:LTS

    Versions
    • 1.5.7-2build1
    • 1.6.6-1build1
    • 1.6.7-1
    Affected ranges
    • ECOSYSTEM: < 1.6.7-1ubuntu0.1~esm1

    Update to 1.6.7-1ubuntu0.1~esm1

  • php-league-commonmark Ubuntu:Pro:24.04:LTS

    Versions
    • 2.3.9-1
    • 2.4.1-1
    • 2.4.2-1
    • 2.4.2-2
    Affected ranges
    • ECOSYSTEM: < 2.4.2-2ubuntu0.1~esm1

    Update to 2.4.2-2ubuntu0.1~esm1

  • php-league-commonmark Ubuntu:25.10

    Versions
    • 2.6.1-2
    • 2.6.2-1
    • 2.7.0-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • php-league-commonmark Ubuntu:26.10

    Versions
    • 2.8.0-1
    • 2.8.2-2
    • 2.8.3-1
    • 2.10.0-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • php-league-commonmark Ubuntu:26.04:LTS

    Versions
    • 2.7.0-1
    • 2.7.1-2
    • 2.8.0-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

Check your server →