Backend users with file write permissions were able to upload form definition files with mixed-case extensions (e.g., .FORM.YAML) to bypass the Form Framework's upload restriction. 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, 11.0.0-11.5.50, 12.0.0-12.4.45, 13.0.0-13.4.30 and 14.0.0-14.3.2.

Affected: Packagist: typo3/cms-core, Packagist: typo3/cms-form

### Problem Backend users with file write permissions were able to upload form definition files with mixed-case extensions (e.g., `.FORM.YAML`) to bypass the Form Framework's upload restriction. Maliciously crafted form definition files can be used to execute arbitrary SQL statements, allowing attackers to escalate privileges by creating administrative backend user accounts.

### Solution Update to TYPO3 versions 10.4.57 ELTS, 11.5.51 ELTS, 12.4.46 ELTS, 13.4.31 LTS, 14.3.3 LTS that fix the problem described.

### Credits TYPO3 CMS thanks Alexander Künzl for reporting this issue, and to TYPO3 core & security team members Oliver Hader and Benjamin Franzke for fixing it.

### Resources * [TYPO3-CORE-SA-2026-008](https://typo3.org/security/advisory/typo3-core-sa-2026-008)

Ein entfernter, authentisierter Angreifer kann mehrere Schwachstellen in TYPO3 Core ausnutzen, um Sicherheitsbeschränkungen zu umgehen, Benutzer auf schädliche Websites umzuleiten, beliebigen Code auszuführen, Berechtigungen zu eskalieren oder andere Auswirkungen zu verursachen.