Home/CVE/league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in th
CVE

CVE-2026-33347

league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in th

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.

MEDIUM · CVSS 6.1 EPSS 0.00015
Schedule remediation
  • SSVC automatable: yes - attacks can be scripted at scale
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-185Incorrect Regular Expression
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-918Server-Side Request Forgery (SSRF)
▤

Affected Products & Versions

1
thephpleague commonmark>= 2.3.0 and < 2.8.2
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
Packagist league/commonmark MEDIUM fixed in 2.8.2
▣

Scoring & Timeline

6.1
MEDIUM · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD24 Mar 2026 · 08:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

1
usnUSN-8194-1
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/thephpleague/commonmark/commit/59fb075d2101740c337c7216e3f32b36c204218bPatch
https://github.com/thephpleague/commonmark/releases/tag/2.8.2ProductRelease Notes
https://github.com/thephpleague/commonmark/security/advisories/GHSA-hh8v-hgvp-g3f5MitigationVendor Advisory
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