CVE-2025-3935
ScreenConnect Exposure to ASP.NET ViewState Code Injection
ConnectWise ScreenConnect Improper Authentication Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.
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.
CISA notes
https://www.connectwise.com/company/trust/security-bulletins/screenconnect-security-patch-2025.4 ; https://nvd.nist.gov/vuln/detail/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.
Severity
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation Context
as of October 17, 2026- CISA added CVE-2025-3935 to the KEV catalog 38 days after its CVE record was published. The median for entries added in 2025 is 26 days.
- It is one of 4 ConnectWise entries in the CISA KEV catalog, and the only one added in 2025.
- Its current EPSS score (3.5%) is higher than that of 14% of CISA KEV entries.
Affected Products
| Vendor | Product | Affected versions |
|---|---|---|
| ConnectWise | ConnectWise ScreenConnect | <25.2.3 |
References
2 LinksRecord Details
More from ConnectWise
Authentication bypass using an alternate path or channel
Improper limitation of a pathname to a restricted directory (“path traversal”)
ScreenConnect Client: Guest-to-Host File Execution via File-Transfer Actions
Related
Tool categories
CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.