FreePBX is an open source IP PBX. Prior to versions 16.0.39 and 17.0.7, users authenticated via User Control Panel (UCP) are able to execute arbitrary commands on the PBX as the webserver user (typically asterisk) using specially crafted HTTP strings. Authenticated access to UCP is required. Note that this is often more common for less-privileged users to have UCP access vs. the Administrator Control Panel (ACP) access (which is usually FreePBX higher-level administrator accounts only). Insufficient sanitization of certain URL parameters utilized by UCP did not fully account for malicious strings in these fields. This could result in binaries being executed on the host server by carefully chaining commands. This issue has been patched in versions 16.0.39 and 17.0.7.