FreePBX is an open source IP PBX. Prior to versions 16.0.72 and 17.0.7, a critical vulnerability exists in the FreePBX backup Module that allows authenticated attackers to execute arbitrary code on the server. Authentication with a known username that has sufficient access permissions and/or write access to backup files is required. This vulnerability is caused by improper path sanitization in the backup restore functionality, enabling attackers to upload malicious PHP files to the web root directory. This issue has been patched in versions 16.0.72 and 17.0.7.