CVE-2025-3935

ScreenConnect Exposure to ASP.NET ViewState Code Injection

High 8.1
Exploited: added to CISA KEV 2 Jun 2025

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.

Key facts

Published: 25 Apr 2025
Last changed: 26 Feb 2026
Assigned by: ConnectWise
KEV added: 2 Jun 2025
KEV fix due: 23 Jun 2025
EPSS: 3.597% likely to be exploited in the next 30 days, higher than 89.635% of CVEs (scores for 15 Nov 2026)
SSVC (CISA): Exploitation: active; Automatable: no; Technical impact: total

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

8.1CVSS 3.1, Highfrom the CNA (ConnectWise)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

What to do

Cloud: No action is required. On-premises: Upgrade to the latest stable version. Details and guidance can be found here: ScreenConnect 25.2.4 Security Patch https://www.connectwise.com/company/trust/security-bulletins/screenconnect-security-patch-2025.4CNA solution statement
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 KEV required action

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

CAPEC-115 Authentication Bypass (CNA impact statement)

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

Vendor	Product	Versions
ConnectWise	ScreenConnect	Default status: unaffected <25.2.3 (affected)