PowerCMS XMLRPC API provided by Alfasado Inc. contains a command injection vulnerability. Sending a specially crafted message by POST method to PowerCMS XMLRPC API may allow arbitrary Perl script execution, and an arbitrary OS command may be executed through it. Affected products/versions are as follows: PowerCMS 6.021 and earlier (PowerCMS 6 Series), PowerCMS 5.21 and earlier (PowerCMS 5 Series), and PowerCMS 4.51 and earlier (PowerCMS 4 Series). Note that all versions of PowerCMS 3 Series and earlier which are unsupported (End-of-Life, EOL) are also affected by this vulnerability.