---
title: "CVE-2025-3935: ConnectWise ScreenConnect Improper Authentication Vulnerability"
url: https://erroneo.us/security/cve/CVE-2025-3935/
description: "CVE-2025-3935 (ConnectWise ScreenConnect): Exploited in the wild (CISA KEV). ScreenConnect versions 25.2.3 and earlier versions may be susceptible to a…"
type: vulnerability-record
section: "Security Digest"
date_published: 2025-04-25
date_modified: 2026-02-26
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2025-3935"
kev: true
cvss: 8.1
epss: 0.03536
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2025-3935: ConnectWise ScreenConnect Improper Authentication Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run ConnectWise ScreenConnect. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2025-06-02, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2025-06-23 ; treat that as the outer limit, not the target.
- EPSS 3.5% , percentile 89: FIRST’s model estimates a 3.5% chance of exploitation activity in the next 30 days, higher than 89% of all scored CVEs (elevated). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.

## What it is

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 products (CVE record)

- ConnectWise ScreenConnect: <25.2.3

## Severity

- ConnectWise CVSS 3.1: 8.1 `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: added 2025-06-02; federal due date 2025-06-23. Known ransomware use: Unknown.
- CISA 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.
- CISA SSVC assessment: exploitation active , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 3.54% probability of exploitation activity in the next 30 days; percentile 89.

## Sources

- [Listed in CISA KEV notes (connectwise.com)](https://www.connectwise.com/company/trust/security-bulletins/screenconnect-security-patch-2025.4)
- [CVE.org record CVE-2025-3935](https://www.cve.org/CVERecord?id=CVE-2025-3935)
- [NVD entry CVE-2025-3935](https://nvd.nist.gov/vuln/detail/CVE-2025-3935)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-3935)
- [connectwise.com](https://www.connectwise.com/company/trust/advisories)

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Source page: https://erroneo.us/security/cve/CVE-2025-3935/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt