This advisory has been withdrawn because it is a duplicate of GHSA-9ccq-2jfg-qw33. This link is maintained to preserve external references.
Grav CMS before 2.0.16 contains an origin validation bypass in the Uri::referrer() and Pages::referrerRoute() methods, which validate the Referer header using an unanchored string prefix match (str_starts_with($referrer, $base)) with no trailing delimiter. An attacker who controls a domain that begins with the victim site's origin (e.g. https://example.com.attacker.tld) can send a request with such a Referer to be treated as same-origin, bypassing the Referer-based origin check.
{
"cwe_ids": [
"CWE-346"
],
"github_reviewed": true,
"github_reviewed_at": "2026-09-17T20:24:25Z",
"nvd_published_at": "2026-08-25T02:16:46Z",
"severity": "CRITICAL"
}