The most effective fix is to move to a modern version (currently 6.x). Version 5.1.22 was explicitly listed as having unpatched low-severity issues in some advisories, and the RCE flaw was only fully addressed in later updates.
For penetration testers: this is a reliable, high-impact finding in legacy document management systems. Always test op.AddFile.php for direct POST access—it's often overlooked.
: He realized that any software allowing file uploads must strictly enforce "file type" rules to ensure only safe documents enter the system.