Evidence dossier

CVE-2021-34527

Windows Print Spooler Remote Code Execution Vulnerability

82.097.5Priority evidence range
As known Jul 19, 2026, 5:00 AM UTCgen-56ccdaf9

Normalized restatement

<p>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.</p> <p>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.</p> <p>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 (<strong>Note</strong>: 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):</p> <ul> <li>HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Printers\PointAndPrint</li> <li>NoWarningNoElevationOnInstall = 0 (DWORD) or not defined (default setting)</li> <li>UpdatePromptSettings = 0 (DWORD) or not defined (default setting)</li> </ul> <p><strong>Having NoWarningNoElevationOnInstall set to 1 makes your system vulnerable by design.</strong></p> <p>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 <a href="https://support.microsoft.com/topic/31b91c02-05bc-4ada-a7ea-183b129578a7">KB5005010: Restricting installation of new printer drivers after applying the July 6, 2021 updates</a>.</p> <p>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.</p>

State
PUBLISHED
Published
Jul 2, 2021
Updated
Jan 12, 2026
Evidence coverage
85%
CISA KEVCatalog member

Apply updates per vendor instructions.

FIRST EPSS99.76%

2026-07-18 · v2026.06.15 · percentile 100.0%

Source stateNo scored conflict

Distinct CVSS assessments remain side by side; none are averaged.

Source comparison

Who said what

CISA-ADPindependent enrichment
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CISA ADP Vulnrichment

CVEderivative copy
container

CVE Program Container

microsoftoriginal assertion
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Windows Print Spooler Remote Code Execution Vulnerability

CISA KEVoriginal assertion
observed_exploitation

Microsoft Windows Print Spooler Remote Code Execution Vulnerability

FIRST EPSSoriginal assertion
model_probability

Probability 0.997590000000; percentile 0.999550000000

Applicability

Cited product scope

Trace impact →
MicrosoftWindows 10 Version 1507
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.10240.18969", "versionType": "custom"}]unknown
MicrosoftWindows 10 Version 1607
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.14393.4470", "versionType": "custom"}]unknown
MicrosoftWindows 10 Version 1809
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.17763.2029", "versionType": "custom"}]unknown
MicrosoftWindows 10 Version 20H2
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19042.1083", "versionType": "custom"}]unknown
MicrosoftWindows 10 Version 21H2
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19044.1415", "versionType": "custom"}]unknown
MicrosoftWindows 10 Version 22H2
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19045.2251", "versionType": "custom"}]unknown
MicrosoftWindows 11 version 21H2
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.22000.318", "versionType": "custom"}]unknown
MicrosoftWindows 11 version 22H2
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.22621.674", "versionType": "custom"}]unknown
MicrosoftWindows 8.1
[{"status": "affected", "version": "6.3.0", "lessThan": "6.3.9600.20046", "versionType": "custom"}]unknown
MicrosoftWindows Server 2008 R2 Service Pack 1
[{"status": "affected", "version": "6.1.0", "lessThan": "6.1.7601.25633", "versionType": "custom"}]unknown
MicrosoftWindows Server 2008 R2 Service Pack 1 (Server Core installation)
[{"status": "affected", "version": "6.0.0", "lessThan": "6.1.7601.25633", "versionType": "custom"}]unknown
MicrosoftWindows Server 2008 Service Pack 2
[{"status": "affected", "version": "6.0.0", "lessThan": "6.0.6003.21138", "versionType": "custom"}]unknown
MicrosoftWindows Server 2008 Service Pack 2
[{"status": "affected", "version": "6.0.0", "lessThan": "6.0.6003.21138", "versionType": "custom"}]unknown
MicrosoftWindows Server 2008 Service Pack 2 (Server Core installation)
[{"status": "affected", "version": "6.0.0", "lessThan": "6.0.6003.21138", "versionType": "custom"}]unknown
MicrosoftWindows Server 2012
[{"status": "affected", "version": "6.2.0", "lessThan": "6.2.9200.23383", "versionType": "custom"}]unknown
MicrosoftWindows Server 2012 R2
[{"status": "affected", "version": "6.3.0", "lessThan": "6.3.9600.20046", "versionType": "custom"}]unknown
MicrosoftWindows Server 2012 R2 (Server Core installation)
[{"status": "affected", "version": "6.3.0", "lessThan": "6.3.9600.20046", "versionType": "custom"}]unknown
MicrosoftWindows Server 2012 (Server Core installation)
[{"status": "affected", "version": "6.2.0", "lessThan": "6.2.9200.23383", "versionType": "custom"}]unknown
MicrosoftWindows Server 2016
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.14393.4470", "versionType": "custom"}]unknown
MicrosoftWindows Server 2016 (Server Core installation)
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.14393.4470", "versionType": "custom"}]unknown
MicrosoftWindows Server 2019
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.17763.2029", "versionType": "custom"}]unknown
MicrosoftWindows Server 2019 (Server Core installation)
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.17763.2029", "versionType": "custom"}]unknown
MicrosoftWindows Server 2022
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.20348.230", "versionType": "custom"}]unknown
MicrosoftWindows Server version 20H2
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19042.1083", "versionType": "custom"}]unknown
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_10_1507:*:*:*:*:*:*:*:*; end excluding 10.0.10240.18969supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:*:*; end excluding 10.0.14393.4470supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:*:*; end excluding 10.0.17763.2029supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_10_20h2:*:*:*:*:*:*:*:*; end excluding 10.0.19042.1083supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:*:*; end excluding 10.0.19044.1415supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:*:*; end excluding 10.0.19045.2251supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_11_21h2:*:*:*:*:*:*:*:*; end excluding 10.0.22000.318supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_11_22h2:*:*:*:*:*:*:*:*; end excluding 10.0.22621.674supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_7:-:sp1:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_8.1:-:*:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_rt_8.1:-:*:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:*supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*; end excluding 10.0.14393.4470supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*; end excluding 10.0.17763.2029supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*; end excluding 10.0.20348.230supported
Unknown vendorUnknown product
cpe:2.3:o:microsoft:windows_server_20h2:*:*:*:*:*:*:*:*; end excluding 10.0.19042.1083supported

Assessments

CVSS by origin

9.0
nvd@nist.govCVSS 2.0 · role PrimaryAV:N/AC:L/Au:S/C:C/I:C/A:C
8.8
nvd@nist.govCVSS 3.1 · role SecondaryCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.8
secure@microsoft.comCVSS 3.1 · role SecondaryCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.8
microsoftCVSS 3.1 · role unknownCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

Limitations and unknowns

  • KEV membership is authoritative for the catalog, not proof of exposure in any environment.
  • EPSS is a dated model probability and not an individual-environment prediction.
  • Affected or fixed status applies only to the exact cited product and version scope; unresolved scope remains unknown.
  • NVD-carried upstream facts remain derivative and are not independent corroboration.
  • Only NVD metrics validated under the generation-bound calculator are Public Priority eligible; direct CVE record metrics remain display-only.
  • NVD CVSS source eligibility is closed: NVD-authored, exact record-source, or registered same-CVE container origin; unmapped sources remain display-only.
  • Factor D is unknown in Public Core because no accepted canonical mapping-obligation ledger is present.
  • Core replay supports the active and immediately prior generation; retrospective valid-at replay is deferred.