CVEvulnerability
CVE-2025-3935
CISA Known Exploited Vulnerability
ConnectWise ScreenConnect Improper Authentication Vulnerability — ConnectWise ScreenConnect
ConnectWise ScreenConnect contains an improper authentication vulnerability. This vulnerability could allow a ViewState code injection attack, which could allow remote code execution if machine keys are compromised.
- Added to KEV
- 2025-06-02
- Remediation due
- 2025-06-23
- 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.
- Notes
- https://www.connectwise.com/company/trust/security-bulletins/screenconnect-security-patch-2025.4 ; https://nvd.nist.gov/vuln/detail/CVE-2025-3935
- Status
- Analyzed
- Published
- 2025-04-25
- Last modified
- 2026-06-17
- Assigner
- 7d616e1a-3288-43b1-a0dd-0a65d3e70a49
- CVSS 3.1 (7d616e1a-3288-43b1-a0dd-0a65d3e70a49)
- 8.1 HIGH — CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CVSS 3.1 ([email protected])
- 7.2 HIGH — CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
- Weaknesses
- CWE-502
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.
Affected configurations
• connectwise screenconnect (< 25.2.4)
Related
Weakness · CWE (1)
- CWE-502 Deserialization of Untrusted Data weakness