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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 3 May 2022. Known ransomware use
Windows 10 1507Operating system · Microsoft

CVE-2021-34527

HIGH · 8.8 CVSS v3.1 Published 2021-07-02
Fix available
A fix is available. Upgrade to 10.0.10240.18969 / 10.0.14393.4470 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Ransomware High EPSS Public exploit Remotely reachable Zero-click Patch available

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 remote code execution vulnerability exists when the Windows Print Spooler service improperly performs privileged file operations. An attacker who successfully exploited this vulnerability could run arbitrary code with SYSTEM privileges. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. UPDATE July 7, 2021: The security update for Windows Server 2012, Windows Server 2016 and Windows 10, Version 1607 have been released. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. If you are unable to install these updates, see the FAQ and Workaround sections in this CVE for information on how to help protect your system from this vulnerability. In addition to installing the updates, in order to secure your system, you must confirm that the following registry settings are set to 0 (zero) or are not defined (Note: These registry keys do not exist by default, and therefore are already at the secure setting.), also that your Group Policy setting are correct (see FAQ): HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Printers\PointAndPrint NoWarningNoElevationOnInstall = 0 (DWORD) or not defined (default setting) UpdatePromptSettings = 0 (DWORD) or not defined (default setting) Having NoWarningNoElevationOnInstall set to 1 makes your system vulnerable by design. UPDATE July 6, 2021: Microsoft has completed the investigation and has released security updates to address this vulnerability. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. If you are unable to install these updates, see the FAQ and Workaround sections in this CVE for information on how to help protect your system from this vulnerability. See also KB5005010: Restricting installation of new printer drivers after applying the July 6, 2021 updates. Note that the security updates released on and after July 6, 2021 contain protections for CVE-2021-1675 and the additional remote code execution exploit in the Windows Print Spooler service known as “PrintNightmare”, documented in CVE-2021-34527.

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 · high confidence

CVE-2021-34527 (PrintNightmare) is a remote code execution vulnerability in the Windows Print Spooler service that allows an attacker to run arbitrary code with SYSTEM privileges by improperly handling privileged file operations. This vulnerability affects multiple Windows versions and was actively exploited in the wild.

MitigationInstall Microsoft security updates immediately and verify that registry keys NoWarningNoElevationOnInstall and UpdatePromptSettings under HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Printers\PointAndPrint are set to 0 or not defined (these keys do not exist by default and are already secure).

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 10 1507Operating system
Affected:< 10.0.10240.18969
Windows 10 1607Operating system
Affected:< 10.0.14393.4470
Windows 10 1809Operating system
Affected:< 10.0.17763.2029
Windows 10 20h2Operating system
Affected:< 10.0.19042.1083
Windows 10 21h2Operating system
Affected:< 10.0.19044.1415
Windows 10 22h2Operating system
Affected:< 10.0.19045.2251
Windows 11 21h2Operating system
Affected:< 10.0.22000.318
Windows 11 22h2Operating system
Affected:< 10.0.22621.674

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. Check Windows version against affected ranges
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' and compare the build number to the vulnerable versions: 1507 < 18969, 1607 < 4470, 1809 < 2029, 20h2 < 1083, 21h2 < 1415, 22h2 < 2251, 11 21h2 < 318, 11 22h2 < 674
    Affected if The installed Windows build number falls within any of the version ranges listed as affected
  2. Verify Print Spooler service status
    Run 'Get-Service Spooler' in PowerShell or check Services.msc for the Print Spooler service
    Affected if The Print Spooler service is running (vulnerability requires this service to be active)
  3. Check if Point and Print is enabled
    Run 'Get-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows NT\Printers\PointAndPrint" -Name NoWarningNoElevationOnInstall -ErrorAction SilentlyContinue'
    Affected if The registry value NoWarningNoElevationOnInstall is set to 1 (allows privileged file operations without elevation)

The system is vulnerable if it runs an affected Windows version with Print Spooler active and Point and Print configured with NoWarningNoElevationOnInstall set to 1, or if the version falls below the patched build numbers regardless of configuration.

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.

dbcve · scoped
Upgrade available Upgrade to 10.0.10240.18969 / 10.0.14393.4470 / 10.0.17763.2029 or later
Fixed in 10.0.10240.1896910.0.14393.447010.0.17763.2029
Vendor patch portal.msrc.microsoft.com →
Interim mitigation

Install Microsoft security updates immediately and verify that registry keys NoWarningNoElevationOnInstall and UpdatePromptSettings under HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Printers\PointAndPrint are set to 0 or not defined (these keys do not exist by default and are already secure).

Recommended fix High confidence

Install the respective security update for your Windows 10/11 version (e.g., for Windows 10 21h2: KB5005010 or later cumulative update containing the fix, build 10.0.19044.1415 or higher)

  1. Identify your current Windows version and build number by running 'winver' or 'systeminfo'
  2. Navigate to the Microsoft Security Response Center (MSRC) or use Windows Update to obtain the security update for CVE-2021-34527
  3. Install the applicable security update for your Windows version from the Security Updates table in the CVE entry
  4. After installing the update, verify the Print Spooler registry settings: Check HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Printers\PointAndPrint
  5. Confirm NoWarningNoElevationOnInstall is set to 0 (DWORD) or is not defined (default secure setting)
  6. Confirm UpdatePromptSettings is set to 0 (DWORD) or is not defined (default secure setting)
  7. If either registry value is set to 1, change it to 0 or remove it to secure the system
  8. Restart the Print Spooler service or reboot the system for changes to take effect
Caveat None - this is a security patch; ensure adequate backup and testing window before deploying in production environments

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Windows 10 1507 Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.

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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-2021-34527 in production — separate from our analysis above.

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