CVE-2025-3935
Description
ScreenConnect versions 25.2.3 and earlier versions may be susceptible to a ViewState code injection attack. ASP.NET Web Forms use ViewState to preserve page and control state, with data encoded using Base64 protected by machine keys.
It is important to note that to obtain these machine keys, privileged system level access must be obtained.
If these machine keys are compromised, attackers could create and send a malicious ViewState to the website, potentially leading to remote code execution on the server.
The risk does not originate from a vulnerability introduced by ScreenConnect, but from platform level behavior. This had no direct impact to ScreenConnect Client. ScreenConnect 2025.4 patch disables ViewState and removes any dependency on it.
Summary dbcve.org
ScreenConnect versions 25.2.3 and earlier use ASP.NET Web Forms ViewState (Base64-encoded, machine-key protected) which could allow code injection if machine keys are compromised. This is a platform-level behavior rather than a ScreenConnect-specific vulnerability; attackers with privileged system access could craft malicious ViewState payloads for potential RCE.
Mitigation
Upgrade to ScreenConnect 2025.4 or later which disables ViewState and removes the dependency. Since exploiting this requires prior compromise of machine keys through privileged access, ensure robust system-level security controls are in place.