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.

Scoring

• CVSS: 8.1 (HIGH, 3.1)
• EPSS exploitation probability: Not yet available
• EPSS percentile: Not yet available

CISA KEV status

• Added to KEV: 2025-06-02
• Remediation due date: 2025-06-23
• Known ransomware campaign use: Unknown

Weakness types (CWE)

• CWE-502

References

• https://www.connectwise.com/company/trust/advisories
• https://www.connectwise.com/company/trust/security-bulletins/screenconnect-security-patch-2025.4
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-3935

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