CVE-2025-3935ScreenConnect Exposure to ASP.NET ViewState Code Injection
Updated under an hour ago ()
Does this affect you?
It affects ConnectWise ScreenConnect. Add what you run to find out whether that includes you.
CISA lists it as known exploited since Jun 2, 2025; federal agencies had to remediate by Jun 23, 2025. Treat that date as your deadline.
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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.
- CVSS
- 8.1 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- CWE-502
- Known exploited
- Added to CISA KEV Jun 2, 2025; federal remediation due Jun 23, 2025Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- EPSS (exploitation in the next 30 days)
- 3.54% (percentile 89)
- Assigned by
- ConnectWise
- NVD analysis
- Analyzed
- Record last updated
- Feb 26, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
ConnectWise ScreenConnect connectwise:screenconnect (from the name) | before 25.2.3 | CNA record |
connectwise screenconnect connectwise:screenconnect | before 25.2.4 | NVD |
References
- https://www.connectwise.com/company/trust/security-bulletins/screenconnect-security-patch-2025.4vendor-advisory
- https://www.connectwise.com/company/trust/advisoriesvendor-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-3935us-government-resource
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.