This vulnerability allows remote attackers to execute local PHP files on affected installations of Horde Groupware Webmail Edition 5.2.22. Authentication is required to exploit this vulnerability. The specific flaw exists within edit.php. When parsing the params[template] parameter, the process does not properly validate a user-supplied path prior to using it in file operations. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of the www-data user. Was ZDI-CAN-10469.
https://www.zerodayinitiative.com/advisories/ZDI-20-276/
https://lists.debian.org/debian-lts-announce/2020/04/msg00009.html