On 2025-06-02, CISA added CVE-2025-3935 (ConnectWise ScreenConnect) to its Known Exploited Vulnerabilities (KEV) catalog [2]. The vulnerability is listed in the catalog as "ConnectWise ScreenConnect Improper Authentication Vulnerability" [2]. CISA requires remediation in accordance with the listed vendor mitigation guidance; see the original text in the body for specific requirements [2].
Backfill: this event became public on Jun 2, 2025 and we added it on Nov 10, 2026. It is not a new event.
CISA Adds ConnectWise ScreenConnect Vulnerability CVE-2025-3935 to Known Exploited Vulnerabilities Catalog
1 min read
- Disclosed
- Jun 2, 2025
- Published
- Nov 10, 2026
- Last updated
- Nov 8, 2026
- CVSS basis
- Our assessment
- 3.6%, higher than 90% of CVEs
- Exploitation and patch status
- ExploitedKEV
- Attack vector
- Vulnerability status
- Actor type
- Motivation
On this page
30-second summary
What happened
Who is affected
Industries mainly affected: Government, Cross-industry
What to do nowOur advice
CISA requires remediation in accordance with the listed vendor mitigation guidance; see the original text in the body for specific requirements [2].
Timeline
Technical details
CISA KEV Listing Record
CISA added CVE-2025-3935 (ConnectWise ScreenConnect) to the Known Exploited Vulnerabilities () catalog on 2025-06-02 [2].
Original Technical Description
ConnectWise ScreenConnect contains an improper authentication vulnerability. This vulnerability could allow a ViewState code injection attack, which could allow if machine keys are compromised. [2]
Official 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. [2]
Individual Vulnerability Record
The U.S. National Vulnerability Database (NVD) provides an independent vulnerability record and description for CVE-2025-3935 [1].
References
Official / primary3
- [1]
“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, privil”
- [2]
This site aggregates public information and is not security consulting advice. Test remediation steps before applying.