TYPO3-CORE-SA-2026-008: Broken Access Control in Form Framework
It has been discovered that TYPO3 CMS is susceptible to broken access control.
- Component Type: TYPO3 CMS
- Subcomponent: Form Framework (ext:form)
- Release Date: June 9, 2026
- Vulnerability Type: Broken Access Control
- Affected Versions: 10.0.0-10.4.56, 11.0.0-11.5.50, 12.0.0-12.4.45, 13.0.0-13.4.30, 14.0.0-14.3.2
- Severity: High
- Suggested CVSS: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- References: CVE-2026-47346, CWE-178, CWE-862
Problem Description
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
Thanks to Alexander Künzl for reporting this issue, and to TYPO3 core & security team members Oliver Hader and Benjamin Franzke for fixing it.
General Advice
Follow the recommendations that are given in the TYPO3 Security Guide. Please subscribe to the typo3-announce mailing list.
General Note
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