TYPO3 is an open source PHP based web content management system released under the GNU GPL. The TYPO3-specific `t3://` URI scheme could be used to access resources outside of the users' permission scope. This encompassed files, folders, pages, and records (although only if a valid link-handling configuration was provided). Exploiting this vulnerability requires a valid backend user account. Users are advised to update to TYPO3 versions 8.7.57 ELTS, 9.5.46 ELTS, 10.4.43 ELTS, 11.5.35 LTS, 12.4.11 LTS, 13.0.1 that fix the problem described. There are no known workarounds for this issue.