Backend users with access to the Form Framework were able to use files not ending in .form.yaml as form definitions, which were processed without denying the incorrect file extension. Maliciously crafted form definition files can be used to execute arbitrary SQL statements, allowing attackers to escalate privileges by creating administrative backend user accounts. This issue affects TYPO3 CMS versions before 10.4.57, 11.0.0-11.5.51, 12.0.0-12.4.46, 13.0.0-13.4.31 and 14.0.0-14.3.3.