CVE-2026-33347 — league/commonmark has an embed extension allowed_domains bypass
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 du…
Published: 2026-03-24 · CVSS: 6.3 · CVSS 4.0
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7