CVE-2025-3935

ScreenConnect Exposure to ASP.NET ViewState Code Injection

HIGH

7.2

CVSS Score

Published: April 25, 2025 at 06:27 PM UTC

Updated: June 17, 2026 at 09:20 AM UTC

1 product affected across 1 vendorScreenConnect

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Severity

HIGH7.2

Exploitation

CISA KEV

Exploit prediction

EPSS 4%

SSVC

Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score3.5%

EPSS (Exploit Prediction Scoring System) estimates a 3.5% chance this CVE is exploited in the wild within the next 30 days — higher than 89% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

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.

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.

Ransomware Use

Unknown

Added to KEV

Jun 2, 2025

Remediation Due

Jun 23, 2025

490 days overdue

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.