# CVE-2026-33347: php-league-commonmark: league/commonmark is a PHP Markdown parser

CVE-2026-33347 is fixed in php-league-commonmark on 1 platform, first by php-league-commonmark 1.3.1-1ubuntu2+esm1, released March 24, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-33347
- Priority: Routine
- CVSS: 6.1 (Medium)
- EPSS: 0.0025
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 24, 2026

## Description

league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like youtube.com.evil passes the allowlist check when youtube.com is an allowed domain. This issue has been patched in version 2.8.2.

## 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-2026-33347](https://patchblox.com/security/data/fix/linux/debian-cve-2026-33347.md) | Mar 24, 2026 |
| Linux | php-league-commonmark Debian 13.5 (trixie) | 2.7.0-1+deb13u1 | [DEBIAN-CVE-2026-33347](https://patchblox.com/security/data/fix/linux/debian-cve-2026-33347.md) | Mar 24, 2026 |
| Linux | php-league-commonmark Debian 14 | 2.8.2-1 | [DEBIAN-CVE-2026-33347](https://patchblox.com/security/data/fix/linux/debian-cve-2026-33347.md) | Mar 24, 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 2026-11-08T06:59:42Z 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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