Actively exploited in the wild
ConnectWise ScreenConnect Improper Authentication Vulnerability
ConnectWise - ScreenConnect · Listed in the CISA KEV since 2025-06-02. This indicates confirmed attacks in production environments.
Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CVE-2025-3935
HighCVSS 8.1KEVSummary
ScreenConnect versions 25.2.3 and earlier may be susceptible to a ViewState code injection attack. To obtain the necessary machine keys, privileged system level access must be obtained.
Risk Assessment
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.
Recommendation
Update ScreenConnect to version 2025.4, which disables ViewState and removes any dependency on it.
Other vulnerabilities in ScreenConnect
See all- CVE-2026-3564Critical
A vulnerability in the ScreenConnect server component allows an actor with access to server-level cryptographic material used for authentication to obtain unauthorized access, including elevated privileges, in certain scenarios. ScreenConnect host and guest client agents are not independently affected by this CVE.
- CVE-2025-14265Critical
In ScreenConnect versions prior to 25.8, server-side validation and integrity checks within the extension subsystem could allow the installation and execution of untrusted or arbitrary extensions by authorized or administrative users. Abuse of this behavior could result in the execution of custom code on the server or unauthorized access to application configuration data. This issue affects only the ScreenConnect server component; host and guest clients are not impacted.
- CVE-2026-11596Medium
In ScreenConnect™ versions prior to 26.2, input validation within the Host Pass creation functionality could allow an authenticated user with Host Pass creation privileges to specify a token expiration duration beyond the intended maximum when generating delegated access tokens.
Original NVD description (English source)
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.