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Vulnerabilities

Vulnerability · CVE-2025-3935

ConnectWise ScreenConnect Improper Authentication Vulnerability

Published Apr 25, 2025 · catalog updated Jun 17, 2026 · ConnectWise ScreenConnect

Patch now

CVE-2025-3935 is in the CISA known-exploited catalog, due Jun 23, 2025. Confirm ConnectWise ScreenConnect against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Severity
High8.1
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
3.54%
Remediation
Remediation guidance
Affected products
cpe connectwise/screenconnect · vendor ConnectWise ScreenConnect · vendor ConnectWise ScreenConnect <25.2.3

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe connectwise/screenconnectversion unspecified
  • vendor ConnectWise ScreenConnectversion unspecified
  • vendor ConnectWise ScreenConnect <25.2.3<25.2.3

How to fix CVE-2025-3935

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2025-3935 is in the CISA known-exploited catalog, due Jun 23, 2025. Confirm ConnectWise ScreenConnect against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Compare what you have installed with ConnectWise ScreenConnect <25.2.3 <25.2.3. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

What should an analyst verify?

CWE-287: Improper Authentication; CWE-502: Deserialization of Untrusted Data. EPSS 3.54%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 25, 2025 · Catalog

    Detected

    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 cre

  2. Jun 2, 2025 · CISA KEV

    Known exploited

    Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

  3. Jun 23, 2025 · CISA KEV

    Remediation due

    Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

  4. Jun 17, 2026 · Catalog

    Updated

    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 cre

Sources

  • CISA KEVConfirmed exploitationCVE-2025-3935

    ConnectWise ScreenConnect contains an improper authentication vulnerability. This vulnerability could allow a ViewState code injection attack, which could allow remote code execution if machine keys are compromised.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2025-3935

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-3935

    30-day exploitation probability 3.5%

    first.org
  • EUVDVulnerability recordEUVD-2025-12502

    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 m

    euvd.enisa.europa.eu
  • NIST NVDVulnerability recordCVE-2025-3935

    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

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2025-3935

    ConnectWise ScreenConnect contains an improper authentication vulnerability. This vulnerability could allow a ViewState code injection attack, which could allow remote code execution if machine keys are compromised.

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.