Home/CVE/ConnectWise ScreenConnect Improper Authentication Vulnerability
CVE

CVE-2025-3935

ConnectWise ScreenConnect Improper Authentication Vulnerability

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.

HIGH · CVSS 8.1 ⚠ CISA KEV EPSS 0.06148
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  • Listed on CISA KEV (known exploited in the wild)
  • SSVC exploitation status: active
  • EPSS percentile: top 9% of all CVEs by exploitation likelihood
  • CVSS base score ≥ 7.0
Sigma rules8 YARA rules0

Required Remediation

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

Weakness Classification

Affected Products & Versions

1

Sigma Hunt Rules

8
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
producthighRemote Access Tool - ScreenConnect Server Web Shell Execution
productmediumScreenConnect Temporary Installation Artefact
productmediumRemote Access Tool - ScreenConnect Installation Execution
productmediumRemote Access Tool - ScreenConnect Potential Suspicious Remote Command Execution
productmediumRemote Access Tool - ScreenConnect Execution
productlowRemote Access Tool - ScreenConnect Temporary File

Scoring & Timeline

8.1
HIGH · CVSS v3.1 · 7d616e1a-3288-43b1-a0dd-0a65d3e70a49
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD25 Apr 2025 · 07:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
active
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.

Vendor Advisories

1
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
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