Improper Signature VerificationWeakness · CWE-347

CVE-2026-3564

CRITICAL · 9.0 CVSS v3.1 Published 2026-03-17
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
99/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A condition in the ScreenConnect server component may allow an actor with access to server-level cryptographic material used for authentication to obtain unauthorized access, including elevated privileges, in certain scenarios. ScreenConnect host and guest client agents are not independently affected by this CVE.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A vulnerability in ScreenConnect server allows an attacker with access to server-level cryptographic material used for authentication to gain unauthorized access and elevated privileges. The clients (host and guest agents) are not independently affected, indicating this is purely a server-side authentication weakness related to cryptographic material handling.

MitigationOrganizations should immediately identify and rotate all server-level cryptographic material (certificates, keys, authentication tokens) used by ScreenConnect, review server access logs for unauthorized activity, and monitor for any signs of compromise while awaiting vendor patch.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm ScreenConnect server is installed
    Check for ScreenConnect installation directories (typically C:\Program Files\ScreenConnect or /opt/screenconnect) or look for screenconnect services running on the system
    Affected if ScreenConnect server component is present on the system
  2. Identify ScreenConnect server version
    Check version.json in the ScreenConnect installation directory, or query the ScreenConnect service/API for its version information
    Affected if Installed version falls within any affected version range (compare against vendor-advisory version lists)
  3. Locate server-level cryptographic material
    Examine the ScreenConnect configuration directory for authentication keys, certificates, and credential files (typically in App_Data or configuration folders within the installation)
    Affected if Cryptographic material files exist and are accessible
  4. Verify access controls on cryptographic assets
    Review file system permissions on key/certificate storage directories - check which users/groups have read access to authentication material
    Affected if Untrusted accounts or excessive permissions exist on cryptographic material storage
  5. Check for signs of key compromise
    Review server logs for unusual authentication patterns, unexpected privilege escalation events, or access to cryptographic material from unexpected sources
    Affected if Log evidence shows cryptographic material was accessed by unauthorized or unexpected principals

User is affected if ScreenConnect server is running and an attacker has obtained access to the server's cryptographic keys or authentication credentials used for server-level authentication.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Organizations should immediately identify and rotate all server-level cryptographic material (certificates, keys, authentication tokens) used by ScreenConnect, review server access logs for unauthorized activity, and monitor for any signs of compromise while awaiting vendor patch.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,980
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Scan for this in your stack

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dbcve dependency scanner

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-3564 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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