CVE-2020-15099: Improper Input Validation

In TYPO3 CMS, in a case where an attacker manages to generate a valid cryptographic message authentication code (HMAC-SHA1), it is possible to retrieve arbitrary files of a TYPO3 installation. This includes the possibility to fetch typo3conf/LocalConfiguration.php, which again contains the encryptionKey as well as credentials of the database management system being used. In case a database server is directly accessible either via internet or in a shared hosting network, this allows the ability to completely retrieve, manipulate or delete database contents. This includes creating an administration user account which can be used to trigger remote code execution by injecting custom extensions.