TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 6.2.57, 7.6.51, 8.7.40, 9.5.25, 10.4.14, 11.1.1 it has been discovered that Login Handling is susceptible to open redirection which allows attackers redirecting to arbitrary content, and conducting phishing attacks. No authentication is required in order to exploit this vulnerability. This is fixed in versions 6.2.57, 7.6.51, 8.7.40, 9.5.25, 10.4.14, 11.1.1.