FreePBX is an open source IP PBX. Prior to versions 16.0.10 and 17.0.5, a critical vulnerability exists in the sound language upload and conversion functionality that allows an authenticated attacker to perform arbitrary file writes, leading directly to remote code execution (RCE). Authentication with a known username is required. The vulnerability stems from insufficient path sanitization in the file conversion process, enabling path traversal attacks that place malicious PHP files in the web server's root directory. This issue has been patched in versions 16.0.10 and 17.0.5.