In layman's terms: an attacker with no valid username or password can send a specially crafted HTTP request to the SmarterMail service (typically listening on TCP ports 170, 143, 993, 995, 25, or 587, but ). By exploiting a deserialization flaw or a path traversal coupled with insecure file write operations, the attacker can execute arbitrary commands directly on the underlying Windows server via the SYSTEM account.
Because the exploit grants root system access, an intruder can read, download, or alter all email data, databases, configuration sheets, and user passwords stored on the system. Domain Privilege Escalation smartermail 6919 exploit