The custom GINA/CP module in Zoho ManageEngine ADSelfService Plus before 5.5 build 5517 allows remote attackers to execute code and escalate privileges via spoofing. It does not authenticate the intended server before opening a browser window. An unauthenticated attacker capable of conducting a spoofing attack can redirect the browser to gain execution in the context of the WinLogon.exe process. If Network Level Authentication is not enforced, the vulnerability can be exploited via RDP. Additionally, if the web server has a misconfigured certificate then no spoofing attack is required