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Windows 10Operating system · Microsoft

CVE-2021-1674

HIGH · 8.8 CVSS v3.1 Published 2021-01-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable 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
Windows Remote Desktop Protocol Core Security Feature Bypass Vulnerability

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

This is a security feature bypass vulnerability in Windows Remote Desktop Protocol (RDP) Core. The vulnerability allows attackers to circumvent security controls in RDP, potentially enabling unauthorized access or privileged operations. The high CVSS score of 8.8 indicates significant risk, likely due to the critical nature of RDP in enterprise environments.

MitigationApply the relevant Microsoft security patches for this vulnerability to all affected Windows systems. Until patches are applied, consider disabling RDP if not business-critical, enforcing Network Level Authentication (NLA), and restricting RDP access through firewall rules to reduce attack surface.

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

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Windows 10Operating system
Affected:all versions= 20h2= 1607= 1803= 1809= 1909= 2004
Windows 7Operating system
Affected:all versions
Windows 8.1Operating system
Affected:all versions
Windows Rt 8.1Operating system
Affected:all versions
Windows Server 2008Operating system
Affected:= r2
Windows Server 2012Operating system
Affected:all versions= r2
Windows Server 2016Operating system
Affected:all versions= 20h2= 1909= 2004
Windows Server 2019Operating system
Affected:all versions

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
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/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. Verify RDP is enabled on the system
    Check the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server for value 'fDenyTSConnections' - a value of 0 means RDP is enabled. Alternatively, run 'Get-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\Terminal Server' -Name fDenyTSConnections' in PowerShell.
    Affected if RDP is enabled (fDenyTSConnections = 0) on any Windows version listed as affected
  2. Determine the installed Windows version
    Run 'winver' from command prompt, or run 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' or check the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion
    Affected if The Windows version matches any of the affected versions listed: Windows 10 (20h2, 1607, 1803, 1809, 1909, 2004), Windows 7 (all), Windows 8.1 (all), Windows Rt 8.1, Windows Server 2008 R2, Windows Server 2012/2012 R2, Windows Server 2016 (all versions, 20h2, 1909, 2004), Windows Server 2019 (all ve
  3. Confirm the Windows build number for version-specific releases
    Run 'winver' or check the registry HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion for 'CurrentBuild' and 'DisplayVersion' values to identify specific releases like 20h2, 1909, or 2004.
    Affected if The build number corresponds to an affected release (such as Windows 10 20h2 with build 19042, or Windows Server 2016 20h2, 1909, or 2004)
  4. Check if the RDP Core components are loaded
    Verify the Terminal Services service (TermService) is running by running 'Get-Service TermService' in PowerShell or 'sc query TermService' in command prompt.
    Affected if The TermService is running, indicating RDP Core components are active on the system

A system is affected if it runs an affected Windows version (including Windows 7, 8.1, 10, or Windows Server 2008 R2 through 2019) AND has RDP enabled with the TermService running.

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

Apply the relevant Microsoft security patches for this vulnerability to all affected Windows systems. Until patches are applied, consider disabling RDP if not business-critical, enforcing Network Level Authentication (NLA), and restricting RDP access through firewall rules to reduce attack surface.

Fix this in Windows 10 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2021-1674 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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
  • No spam, self-promotion, credentials, or personal data