The vulnerability is publicly known since at least 2015.
Vulnerable component: jQuery File Upload
CVSSv3 score: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C
CWE-ID: CWE-434 - Unrestricted Upload of File with Dangerous Type
The vulnerability allows a remote attacker to compromise vulnerable system.
The vulnerability exists in the plugin's source code that handles file uploads to PHP servers due to software allows upload of arbitrary files to the system. A remote unauthenticated attacker can upload arbitrary .htaccess file to impose security restrictions to its upload folder and upload backdoors and web shells.