A critical security patch has been issued by WHMCS for all versions, from 4.0 right up to the newly released version 5.0 .
Applying the new WHMCS Security Patch is very simple.
It’s just a single file to update. There are separate versions of the file for each release of WHMCS from V4.0 up to the very latest V5.0 release.
The WHMCS Security Patch download consists of a single file which just needs to be unzipped, and then uploaded to the /includes/ folder replacing the existing file.
Please submit the support ticket for WHMCS Security Patch Download links.