TYPO3 before 13.3.1 allows denial of service (interface error) in the Bookmark Toolbar (ext:backend), exploitable by an administrator-level backend user account via manipulated data saved in the bookmark toolbar of the backend user interface. The fixed versions are 10.4.46 ELTS, 11.5.40 LTS, 12.4.21 LTS, and 13.3.1.