ConnectWise ScreenConnect Improper Authentication Vulnerability

A remote attacker, without authentication, can achieve full data confidentiality loss, arbitrary modification of data, complete denial of service or system unavailability. Federal agencies are required to remediate by 2025-06-23 under CISA BOD 22-01.

This is a Deserialization of Untrusted Data (CWE-502) vulnerability in ConnectWise ScreenConnect. 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. Exploitation requires remote network access, higher attack complexity, no authentication required, and no user interaction required.

Probably yes if any of these apply:

CISA added this CVE to the Known Exploited Vulnerabilities catalog on 2025-06-02 based on evidence of active exploitation in the wild. Federal agencies required to remediate by 2025-06-23.