CVE-2025-3935

high

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.

https://www.darkreading.com/remote-workforce/connectwise-rotate-code-signing-certificates

https://www.bleepingcomputer.com/news/security/cisa-warns-of-connectwise-screenconnect-bug-exploited-in-attacks/

https://securityaffairs.com/178591/hacking/u-s-cisa-adds-asus-rt-ax55-devices-craft-cms-and-connectwise-screenconnect-flaws-to-its-known-exploited-vulnerabilities-catalog.html

https://www.helpnetsecurity.com/2025/06/02/attackers-breached-connectwise-compromised-customer-screenconnect-instances/

https://www.cisa.gov/news-events/alerts/2025/06/02/cisa-adds-five-known-exploited-vulnerabilities-catalog

https://www.theregister.com/2025/05/30/connectwise_compromised_by_sophisticated_government/

https://www.securityweek.com/connectwise-discloses-suspected-state-sponsored-hack/

https://thehackernews.com/2025/05/connectwise-hit-by-cyberattack-nation.html

https://securityaffairs.com/178442/hacking/connectwise-cyberattack-sophisticated-nation-state-actor.html

https://www.bleepingcomputer.com/news/security/connectwise-breached-in-cyberattack-linked-to-nation-state-hackers/

https://www.connectwise.com/company/trust/security-bulletins/screenconnect-security-patch-2025.4

https://www.connectwise.com/company/trust/advisories

Details

Source: Mitre, NVD

Published: 2025-04-25

Updated: 2025-06-03

Known Exploited Vulnerability (KEV)

Risk Information

CVSS v2

Base Score: 8.3

Vector: CVSS2#AV:N/AC:L/Au:M/C:C/I:C/A:C

Severity: High

CVSS v3

Base Score: 7.2

Vector: CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Severity: High

EPSS

EPSS: 0.19467

Vulnerability Watch

Tenable Research has classified this CVE under the following Vulnerability Watch classification, which includes active and historical (inactive) classifications. You can learn more about these classifications on our blog.

Vulnerability Being Monitored

Detections

Analytics