The remote web server suffers from a format string vulnerability.
The remote host is running Easy File Sharing Web Server, a file sharing application / web server for Windows. The version of Easy File Sharing Web Server installed on the remote host may crash if it receives requests with an option parameter consisting of a format string. It is unknown whether this issue can be exploited to execute arbitrary code on the remote host, although it is likely the case. In addition, the application reportedly allows remote users to upload arbitrary files to arbitrary locations on the affected host. An attacker may be able to leverage this issue to completely compromise the host by placing them in the startup folder and waiting for a reboot. Additionally, it fails to sanitize input to the 'Description' field when creating a folder or uploading a file, which could lead to cross-site scripting attacks. Note that by default the application runs with the privileges of the user who started it, although it can be configured to run as a service.
Upgrade or patch according to vendor recommendations.