The BackWPup plugin for WordPress is vulnerable to Local File Inclusion via the blockname parameter of the /wp-json/backwpup/v1/getblock REST endpoint in all versions up to, and including, 5.6.6 due to a non-recursive strreplace() sanitization of path traversal sequences. This makes it possible for authenticated attackers, with Administrator-level access and above, to include arbitrary PHP files on the server via crafted traversal sequences (e.g., ....//), which can be leveraged to read sensitive files such as wp-config.php or achieve remote code execution in certain configurations. Administrators have the ability to grant individual users permission to handle backups, which may then allow lower-level users to exploit this vulnerability.

Unauthenticated Cross Site Scripting (XSS) in BackWPup <= 5.7.4 versions.

The BackWPup plugin for WordPress is vulnerable to Directory Traversal in versions up to, and including, 4.0.1 via the job-specific backup folder. This allows authenticated attackers to store backups in arbitrary folders on the server provided they can be written to by the server. Additionally, default settings will place an index.php and a .htaccess file into the chosen directory (unless already present) when the first backup job is run that are intended to prevent directory listing and file access. This means that an attacker could set the backup directory to the root of another site in a shared environment and thus disable that site.

The BackWPup WordPress plugin before 5.7.7 does not properly restrict the destination path of files extracted during a backup restore when its fallback archive library is used, allowing high-privileged users to write files outside the intended restore directory, potentially leading to remote code execution.

The BackWPup – WordPress Backup & Restore Plugin plugin for WordPress is vulnerable to unauthorized access of data due to a missing capability check on the 'backwpupworking' AJAX action in all versions up to, and including, 5.5.0. This makes it possible for authenticated attackers, with Subscriber-level access and above, to retrieve access to a back-up's filename while a backup is running. This information has little value on it's own, but could be used to aid in a brute force attack to retrieve back-up contents in limited environments (i.e. NGINX).