CVE-2026-33347

MEDIUM EPSS 15.1%
Published Mar 24, 20263mo ago · Modified Jun 17, 20262w ago
6.3 CVSS 4.0
Medium
Find Similar
Published Mar 24, 2026 3mo ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
6.3
Exploitability
—
Impact
—
Vector string
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope X

Threat Intelligence

EPSS Exploit Probability
15.1% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 3

CWE-185
CWE-79 Cross-site Scripting Injection
CWE-918 Server-Side Request Forgery (SSRF) Validation

Affected Products 1

VendorProductVersionRange
thephpleaguecommonmark*≥2.3.0  –  <2.8.2

References 3

  • github.com https://github.com/thephpleague/commonmark/commit/59fb075d2101740c337c7216e3f32b36c204218b
    Patch
  • github.com https://github.com/thephpleague/commonmark/releases/tag/2.8.2
    ProductRelease Notes
  • github.com https://github.com/thephpleague/commonmark/security/advisories/GHSA-hh8v-hgvp-g3f5
    MitigationVendor Advisory

Remediation

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