High 8.8Known exploited (CISA KEV)Published Jul 2, 2021

CVE-2021-34527Windows Print Spooler Remote Code Execution Vulnerability

Updated under an hour ago (Oct 27, 2026, 4:20 PM ET)

Does this affect you?

It affects Microsoft Windows 10 Version 1507 and 21 other products. Add what you run to find out whether that includes you.

CISA lists it as known exploited since Nov 3, 2021; federal agencies had to remediate by May 3, 2022, and it is known to be used in ransomware. Treat that date as your deadline.

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Every CVE for Microsoft Windows 10 Version 1507

Exploited in the last 30 days

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.

CVSS: 8.8 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
Weakness (CWE): Not given
Known exploited: Added to CISA KEV Nov 3, 2021; federal remediation due May 3, 2022; known ransomware useApply updates per vendor instructions.
EPSS (exploitation in the next 30 days): 99.79% (percentile 100)
Assigned by: microsoft
NVD analysis: Analyzed
Record last updated: Aug 10, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Microsoft Windows 10 Version 1507 microsoft:windows_10_1507	from 10.0.10240.0 before 10.0.10240.18969	CNA record
Microsoft Windows 10 Version 1607 microsoft:windows_10_1607	from 10.0.14393.0 before 10.0.14393.4470	CNA record
Microsoft Windows 10 Version 1809 microsoft:windows_10_1809	from 10.0.17763.0 before 10.0.17763.2029	CNA record
Microsoft Windows 10 Version 20H2 microsoft:windows_10_20h2	from 10.0.0 before 10.0.19042.1083	CNA record
Microsoft Windows 10 Version 21H2 microsoft:windows_10_21h2	from 10.0.19044.0 before 10.0.19044.1415	CNA record
Microsoft Windows 10 Version 22H2 microsoft:windows_10_22h2	from 10.0.19045.0 before 10.0.19045.2251	CNA record
Microsoft Windows 11 version 21H2 microsoft:windows_11_21h2	from 10.0.22000.0 before 10.0.22000.318	CNA record
Microsoft Windows 11 version 22H2 microsoft:windows_11_22h2	from 10.0.22621.0 before 10.0.22621.674	CNA record
Microsoft Windows 8.1 microsoft:windows_8.1 (from the name)	from 6.3.0 before 6.3.9600.20046	CNA record
Microsoft Windows Server 2008 R2 Service Pack 1 microsoft:windows_server_2008_r2_service_pack_1 (from the name)	from 6.1.7601.0 before 6.1.7601.25633	CNA record
1–10 of 34

References

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34527	vendor-advisory, patch
http://packetstormsecurity.com/files/167261/Print-Spooler-Remote-DLL-Injection.html	exploit, third-party-advisory, vdb-entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34527	mitigation, patch, vendor-advisory
https://www.kb.cert.org/vuls/id/383432	third-party-advisory, us-government-resource
https://www.vicarius.io/vsociety/posts/cve-2021-34527-printnightmare-detection-script	exploit, third-party-advisory
https://www.vicarius.io/vsociety/posts/cve-2021-34527-printnightmare-mitigation-script	exploit, third-party-advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34527	us-government-resource

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.