This indicates an attack attempt to exploit an Authentication Bypass Vulnerability in FreePBX.
A remote unauthenticated attacker could exploit this vulnerability by sending a crafted request to the vulnerable application. Successful exploitation could lead to the execution privileged commands on the target server.
FreePBX prior to 22.214.171.124
FreePBX prior to 126.96.36.199
FreePBX prior to 188.8.131.52
Privilege Escalation: Remote attackers can leverage their privileges on vulnerable systems.
Apply the latest update from the vendor.