CVE-2025-3935

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. It has a CVSS v3.1 base score of 8.1 (HIGH). This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, indicating active exploitation in the wild.

CVE-2025-3935 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

CVE-2025-3935 affects products from connectwise, specifically: screenconnect. Check the affected products table above for specific version ranges.

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.