VulnerabilityAnalyzed

CVE-2026-33347

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.

MEDIUM 6.3EPSS 0.24%

Does this matter?

Lower severity and a low EPSS score (0.24%). Track it; it rarely justifies an emergency change on its own.

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 4.0: 6.3 MEDIUMCVSS: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/M
EPSS: 0.24% probability · 15th percentile
CISA KEV: Not listed
Weakness: CWE-79, CWE-185, CWE-918
Affected: thephpleague/commonmark
Source: security-advisories@github.com

References

https://github.com/thephpleague/commonmark/commit/59fb075d2101740c337c7216e3f32b36c204218bPatch
https://github.com/thephpleague/commonmark/releases/tag/2.8.2Product, Release Notes
https://github.com/thephpleague/commonmark/security/advisories/GHSA-hh8v-hgvp-g3f5Mitigation, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.