It has been discovered that TYPO3 CMS is vulnerable to arbitrary code execution.

Problem Description

Due to the lack of separating user-submitted data from the internal configuration in the Form Designer backend module, it was possible to inject code instructions to be processed and executed via TypoScript as PHP code.

The existence of individual TypoScript instructions for a particular form item (known as formDefinitionOverrides) and a valid backend user account with access to the form module are needed to exploit this vulnerability.

Solution

Update to TYPO3 versions 8.7.49 ELTS, 9.5.38 ELTS, 10.4.33, 11.5.20, 12.1.1 that fix the problem described above.

Credits

Thanks to Sabine Deeken who reported this issue and to TYPO3 core team member Ralf Zimmermann who fixed the issue.

General Advice

Follow the recommendations that are given in the TYPO3 Security Guide. Please subscribe to the typo3-announce mailing list.

General Note

All security related code changes are tagged so that you can easily look them up in our review system.