Untrusted users can inject malicious code into the canonical tag, which is then executed on the web page (front end).
Update to Contao 4.13.3.
Disable canonical tags in the root page settings.
https://contao.org/en/security-advisories/cross-site-scripting-via-canonical-url
If you have any questions or comments about this advisory, open an issue in contao/contao.
{ "nvd_published_at": "2022-05-06T00:15:00Z", "cwe_ids": [ "CWE-79" ], "severity": "HIGH", "github_reviewed": true, "github_reviewed_at": "2022-05-20T19:54:56Z" }