ConnectWise · ScreenConnect · ConnectWise ScreenConnect Improper Authentication Vulnerability
Verdict
Patch soon · actively exploited, reachable from the internet without credentials, and in the top 25% of CVEs by near-term exploitation probability
Added to CISA KEV 2025-06-02 · exploited in the wild for 482 days
CVSS 8.1 HIGH. The score is a summary; these three components are the part that decides whether something scanning the internet can use it.
| Attack vector | networkreachable over the network, with no local access needed |
|---|---|
| Privileges required | noneneeds no credentials at all |
| User interaction | nonecan be triggered with nobody interacting with the page or request |
| Base vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Weakness | CWE-502 |
This describes the vulnerability. It says nothing about whether your systems run it.
EPSS puts the probability of exploitation in the next 30 days at 0.0351, which places it in the top 25% of all tracked CVEs. The percentile is the more useful half: 0.18 in absolute terms sounds low until you know most of the internet-facing software in the world scores under that.
| EPSS probability | 0.0351 |
|---|---|
| Percentile | 0.888 — top 25% |
| Added to KEV | 2025-06-02 |
|---|---|
| Days exploited | 482 |
| Federal remediation due | not set |
| Ransomware use | no known ransomware campaign use |
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
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.