CVE-2026-33347

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.

CVSS v3 6.1 MEDIUM

6.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/thephpleague/commonmark/commit/59fb075d2101740c337c7216e3f32b36c204218b	Patch
https://github.com/thephpleague/commonmark/releases/tag/2.8.2	Product Release Notes
https://github.com/thephpleague/commonmark/security/advisories/GHSA-hh8v-hgvp-g3f5	Mitigation Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:thephpleague:commonmark:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-03-24 20:16

Updated : 2026-06-17 10:37

NVD link : CVE-2026-33347

Mitre link : CVE-2026-33347

CVE.ORG link : CVE-2026-33347

JSON object : View

Products Affected

thephpleague

commonmark

CWE

CWE-79

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CWE-185

Incorrect Regular Expression

CWE-918

Server-Side Request Forgery (SSRF)

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