CVE-2026-33347
March 24, 2026
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.
Affected Packages
league/commonmark (PHP):
Affected version(s) >=2.3.0 <2.8.2Fix Suggestion:
Update to version 2.8.2league/commonmark (PHP):
Affected version(s) >=2.3.0 <2.8.2Fix Suggestion:
Update to version 2.8.2league/commonmark (PHP):
Affected version(s) >=2.3.0 <2.8.2Fix Suggestion:
Update to version 2.8.2league/commonmark (PHP):
Affected version(s) >=2.3.0 <2.8.2Fix Suggestion:
Update to version 2.8.2league/commonmark (PHP):
Affected version(s) >=2.3.0 <2.8.2Fix Suggestion:
Update to version 2.8.2Related Resources (5)
Do you need more information?
Contact UsCVSS v4
Base Score:
6.3
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
LOW
Vulnerable System Availability
NONE
Subsequent System Confidentiality
LOW
Subsequent System Integrity
LOW
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.8
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Weakness Type (CWE)
EPSS
Base Score:
0.04
