CVE-2026-33347

medium

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.

References

https://github.com/thephpleague/commonmark/security/advisories/GHSA-hh8v-hgvp-g3f5

https://github.com/thephpleague/commonmark/releases/tag/2.8.2

https://github.com/thephpleague/commonmark/commit/59fb075d2101740c337c7216e3f32b36c204218b

Details

Source: Mitre, NVD

Published: 2026-03-24

Updated: 2026-03-24

Risk Information

CVSS v2

Base Score: 7.5

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P

Severity: High

CVSS v3

Base Score: 9.8

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Severity: Critical

CVSS v4

Base Score: 6.3

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N

Severity: Medium