CVE-2025-3935ScreenConnect Exposure to ASP.NET ViewState Code Injection
- 8.1HighCVSS base score
- 3.6%Exploitation in 30 daysEPSS · top 10% of all CVEs
- YesKnown exploitedin CISA's KEV since 2 Jun 2025
- YesPublic exploitsa reference or SSVC says so
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.
Exploited in the wild
CISA lists this vulnerability in its Known Exploited Vulnerabilities catalog as ConnectWise ScreenConnect Improper Authentication Vulnerability.
- Added
- 2 Jun 2025
- Fix due (US federal)
- 23 Jun 2025
- Used by ransomware
- Not known
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
ENISA's EU Vulnerability Database lists it as exploited, from CISA's KEV, since 2 Jun 2025.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. CISA's SSVC rates its exploitation: it is being exploited.
Timeline
ID reserved
By ConnectWise
Published
- 38 days later
· 38 days later
Added to CISA KEV
Known exploited in the wild
- 9 months later
· 9 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| ConnectWiseCNA (assigner) | 3.1 | High8.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Analyzed | 3.1 | High7.2 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 3.6% · top 10% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: active · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.1.
Affected products
- affected <25.2.3
What to do
Solution: Cloud: No action is required. On-premises: Upgrade to the latest stable version. Details and guidance can be found here: ScreenConnect 25.2.4 Security Patch https://www.connectwise.com/company/trust/security-bulletins/screenconnect-security-patch-2025.4
References
References3
- https://www.connectwise.com/company/trust/security-bulletins/screenconnect-security-patch-2025.4 (opens in a new tab)
- https://www.connectwise.com/company/trust/advisories (opens in a new tab)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-3935 (opens in a new tab)government-resource
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- CISA KEV catalog (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2025-12502 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2025-3935)Record last updated .