CVE-2026-33347

MEDIUM

league/commonmark 2.3.0-2.8.1 Embed Extension - Domain Allowlist Bypass

Title source: manual
STIX 2.1

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 (3)

Core 3

Scores

CVSS v3 6.1
EPSS 0.0024
EPSS Percentile 14.9%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-185 CWE-79 CWE-918
Status published
Products (3)
league/commonmark 2.3.0 - 2.8.2Packagist
thephpleague/commonmark 2.3.0 - 2.8.2
thephpleague/commonmark >= 2.3.0, < 2.8.2
Published Mar 24, 2026
Tracked Since Mar 25, 2026