AVideo: unauthenticated installer writes PHP config, enabling remote code execution

AVideo is a video-sharing Platform. Prior to 8.1.0, the unauthenticated installer endpoint install/checkConfiguration.php assembles videos/configuration.php by interpolating request parameters, including webSiteRootURL, into single-quoted PHP string literals without escaping. An attacker can terminate a literal and inject PHP that executes as the web-server user when the generated, directly requestable file is loaded. Exploitation requires videos/configuration.php to be absent, as on every fresh deployment or after the file is removed or moved; an existing file blocks this endpoint. The supplied systemRootPath must contain index.php and a connection using databaseHost, databaseUser, and databasePass must succeed, but the attacker can point those parameters to their own database server and needs no target credentials. The write location is also derived from systemRootPath without a base-directory constraint. This permits arbitrary command execution, reading and overwriting files owned by the web-server user, persistent PHP code, and control over stored database connection settings. The endpoint additionally interpolates request values into streamer and configuration INSERT statements, creating a secondary SQL-injection sink. This issue is fixed in version 8.1.0.