When using subrequest authentication, Anubis did not perform validation of the redirect URL and redirects user to any URL scheme. While most modern browsers do not allow a redirect to javascript: URLs, it could still trigger dangerous behavior in some cases.
GET https://example.com/.within.website/?redir=javascript:alert() responds with Location: javascript:alert().
Anybody with a subrequest authentication seems affected. Using javascript: URLs will probably be blocked by most modern browsers, but using custom protocols for third-party applications might still trigger dangerous operations.
This was originally reported by @mbiesiad against Weblate.
{
"github_reviewed": true,
"nvd_published_at": "2025-11-13T03:16:29Z",
"severity": "MODERATE",
"cwe_ids": [
"CWE-601",
"CWE-79"
],
"github_reviewed_at": "2025-10-30T17:08:12Z"
}