---
id: "CVE-2025-3935"
kind: "vulnerability"
aliases: ["CVE-2025-3935"]
title: "connectwise screenconnect: ScreenConnect versions 25.2.3 and earlier versions may be susceptible to a ViewState code injection attack"
severity: "high"
cvss: 8.1
epss: null
exploited: true
status: "open"
category: "vendor"
products: [{"name": "connectwise screenconnect", "fixed": ["25.2.4"], "affected": "< 25.2.4", "ecosystem": "vendor"}, {"name": "ConnectWise ScreenConnect", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["connectwise", "exploited", "screenconnect", "self-hosted", "vendor"]
not_affected_if: ["managed-hosting", "unknown"]
published_at: "2025-04-25T19:15:49+00:00"
first_seen_at: "2026-10-23T19:11:51+00:00"
updated_at: "2026-10-24T00:09:50+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2025-3935", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-3935", "first_seen_at": "2026-10-23T22:29:05+00:00"}]
---

# connectwise screenconnect: ScreenConnect versions 25.2.3 and earlier versions may be susceptible to a ViewState code injection attack

ConnectWise ScreenConnect has an improper authentication flaw that allows ViewState code injection, which can lead to remote code execution if machine keys are compromised. CISA lists it as actively exploited in the wild.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:connectwise screenconnect affected < 25.2.4 fixed 25.2.4
- vendor:ConnectWise ScreenConnect affected ? fixed ?

## Fix

Apply mitigations per vendor instructions, or discontinue use of the product if mitigations are unavailable (per CISA required action).

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2025-3935
- 2026-10-23T22:29:05+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2025-3935

## From the sources

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.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_