TYPO3 subject to Uncontrolled Recursion resulting in Denial of Service

TYPO3 is an open source PHP based web content management system. In versions prior to 9.5.38, 10.4.33, 11.5.20, and 12.1.1, requesting invalid or non-existing resources via HTTP triggers the page error handler, which again could retrieve content to be shown as an error message from another page. This leads to a scenario in which the application is calling itself recursively - amplifying the impact of the initial attack until the limits of the web server are exceeded. This vulnerability is very similar, but not identical, to the one described in CVE-2021-21359. This issue is patched in versions 9.5.38 ELTS, 10.4.33, 11.5.20 or 12.1.1.