CVE-2025-3935: ScreenConnect Exposure to ASP.NET ViewState Code Injection
In CISA’s Known Exploited Vulnerabilities catalog: ConnectWise ScreenConnect Improper Authentication Vulnerability.
Added , federal remediation due . Known ransomware use: Unknown.
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.
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.
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H · CWE-502
Status incidents that name it
No tracked status incident names this CVE.
Affected vendors and products
ConnectWise: ScreenConnect
References
- CVE record on cve.org (opens in new tab)
- NVD entry (opens in new tab)
- www.connectwise.com/company/trust/advisories (opens in new tab)
- www.connectwise.com/company/trust/security-bulletins/screenconnect-security-patch-2025.4 (opens in new tab)
- CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (opens in new tab)
- This product uses data from the NVD API but is not endorsed or certified by the NVD. (opens in new tab)
- Known Exploited Vulnerabilities catalog from CISA. (opens in new tab)
- EPSS scores from FIRST (Exploit Prediction Scoring System). (opens in new tab)