Is CVE-2021-34527 actively exploited?

Yes. KEV Intelligence tracks CVE-2021-34527 as a known exploited vulnerability. Confidence is confirmed.

What exploitation activity has KEV Intelligence observed?

KEV Intelligence has not yet recorded sensor-observed exploitation attempts for CVE-2021-34527. Our sensors continue to monitor for activity targeting this CVE.

Which versions are affected?

CVE-2021-34527 affects Microsoft Windows 10 Version 1507 and 22 other products. KEV Intelligence lists 24 version rows; examples include 10.0.10240.0 to < 10.0.10240.18969, 10.0.14393.0 to < 10.0.14393.4470, and 10.0.17763.0 to < 10.0.17763.2029.

Yes. CVE-2021-34527 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

CVE-2021-34527 Exploited in the Wild — Windows 10 Version 1507, Windows 10 Version 1607, Windows 10 Version 1809, Windows 10 Version 20H2, Windows 10 Version 21H2, Windows 10 Version 22H2, Windows 11 version 21H2, Windows 11 version 22H2, Windows 8.1, Windows Server 2008 R2 Service Pack 1, Windows Server 2008 R2 Service Pack 1 (Server Core installation), Windows Server 2008 Service Pack 2, Windows Server 2008 Service Pack 2 (Server Core installation), Windows Server 2012, Windows Server 2012 (Server Core installation), Windows Server 2012 R2, Windows Server 2012 R2 (Server Core installation), Windows Server 2016, Windows Server 2016 (Server Core installation), Windows Server 2019, Windows Server 2019 (Server Core installation), Windows Server 2022, Windows Server version 20H2

Q: How should organizations remediate it?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Q: Is it in CISA KEV?

Yes. CVE-2021-34527 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2021-34527 is Windows Print Spooler Remote Code Execution Vulnerability affecting Microsoft Windows 10 Version 1507 and 22 other products. A remote code execution vulnerability exists when the Windows Print...

Is it exploited?

Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is confirmed.

Who is affected?

Microsoft / Windows 10 Version 1507 affected before 10.0.10240.18969.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Windows Print Spooler Remote Code Execution Vulnerability

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.

Vendor Product Affected Status

Microsoft Windows 10 Version 1507 Before 10.0.10240.18969 Affected

Microsoft Windows 10 Version 1607 Before 10.0.14393.4470 Affected

Microsoft Windows 10 Version 1809 Before 10.0.17763.2029 Affected

Microsoft Windows 10 Version 20H2 Before 10.0.19042.1083 Affected

Microsoft Windows 10 Version 21H2 Before 10.0.19044.1415 Affected

Microsoft Windows 10 Version 22H2 Before 10.0.19045.2251 Affected

Microsoft Windows 11 version 21H2 Before 10.0.22000.318 Affected

Microsoft Windows 11 version 22H2 Before 10.0.22621.674 Affected

Microsoft Windows 8.1 Before 6.3.9600.20046 Affected

Microsoft Windows Server 2008 R2 Service Pack 1 Before 6.1.7601.25633 Affected

Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation) Before 6.1.7601.25633 Affected

Microsoft Windows Server 2008 Service Pack 2 Before 6.0.6003.21138 Affected

Microsoft Windows Server 2008 Service Pack 2 (Server Core installation) Before 6.0.6003.21138 Affected

Microsoft Windows Server 2012 Before 6.2.9200.23383 Affected

Microsoft Windows Server 2012 (Server Core installation) Before 6.2.9200.23383 Affected

Microsoft Windows Server 2012 R2 Before 6.3.9600.20046 Affected

Microsoft Windows Server 2012 R2 (Server Core installation) Before 6.3.9600.20046 Affected

Microsoft Windows Server 2016 Before 10.0.14393.4470 Affected

Microsoft Windows Server 2016 (Server Core installation) Before 10.0.14393.4470 Affected

Microsoft Windows Server 2019 Before 10.0.17763.2029 Affected

Microsoft Windows Server 2019 (Server Core installation) Before 10.0.17763.2029 Affected

Microsoft Windows Server 2022 Before 10.0.20348.230 Affected

Microsoft Windows Server version 20H2 Before 10.0.19042.1083 Affected

View vendor advisory

Published: 02 Jul 2021
Exploitation Reported: 03 Nov 2021
Attack vector: Remote
Complexity: Low
Privileges: Low
User interaction: None

CVE References

CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2021-34527
Windows Print Spooler Remote Code Execution Vulnerability msrc.microsoft.com · Vendor Advisory https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34527

Exploitation evidence

Why KEV Intelligence marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CISA

Recorded 03 Nov 2021

Independent exploitation attestation added to the KEV Intelligence record.

Used in malware

CISA

Recorded 03 Nov 2021

Malware families have been linked to exploitation of this CVE.

Proof of concept available

GitHub

Recorded 01 Jul 2021

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.

Learn about Pro API access

Source	Added
CISA First	2021-11-03 00:00 UTC
CVE	2026-08-10 15:31 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets: 0
User-Agents: 0

Raw values available in Pro and Enterprise.

Scanner coverage

Metasploit template detected 28 Apr 2025.

View Metasploit template

Virtual patch status

No KEV Intelligence virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner	Reference	Detected
Metasploit	https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/windows/dcerpc/cve_2021_1675_printnightmare.rb	28 Apr 2025
Nessus	https://www.tenable.com/plugins/nessus/151488	06 Dec 2022

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

8.8 High

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

EPSS

99.8%

All CVSS Scores

CVSS v3.1 8.8 High

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

CVSS v2.0 9.0 High

AV:N/AC:L/Au:S/C:C/I:C/A:C

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

m8sec/CVE-2021-34527

github · Created 2022-08-23 20:20:45 UTC · 109 stars · AI assessment 90%

PrintNightmare (CVE-2021-34527) PoC Exploit

nemo-wq/PrintNightmare-CVE-2021-34527

github · Created 2021-07-03 15:15:12 UTC · 145 stars · AI assessment 90%

PrintNightmare - Windows Print Spooler RCE/LPE Vulnerability (CVE-2021-34527, CVE-2021-1675) proof of concept exploits

JohnHammond/CVE-2021-34527

github · Created 2021-07-02 12:10:49 UTC · 275 stars · AI assessment 90%

cve_2021_1675_printnightmare

metasploit · Created Unknown

Metasploit module for CVE-2021-34527

Timeline

From disclosure to observed exploitation

10 Aug 2026
KEV confirmed by CVE

Exploitation attested by an external source
28 Apr 2025
Metasploit module available

Exploit module available
06 Dec 2022
Nessus plugin available

Scanner coverage available
03 Nov 2021
Added to CISA KEV

Listed in the CISA Known Exploited Vulnerabilities catalog
03 Nov 2021
First public exploitation report

Exploit observed in malware
02 Jul 2021
CVE published

Vulnerability disclosed publicly
02 Jul 2021
Public PoC available

Public proof-of-concept code published
09 Jun 2021
CVE ID reserved

Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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Evidence confidence and provenance
First-party sensor telemetry
PoC and scanner references
Affected versions and enrichment
Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2021-34527

Free JSON includes basic KEV fields

{
  "cve_id": "CVE-2021-34527",
  "confidence": "Confirmed",
  "cvss_score": 8.8,
  "cvss_estimated": false,
  "epss_score": 0.99792,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}

CVE-2021-34527

What security teams need to know first

Windows Print Spooler Remote Code Execution Vulnerability

Tags

CVE References

Why KEV Intelligence marks this CVE as exploited

Exploited in the wild

Used in malware

Proof of concept available

Known exploited vulnerability sources

Operational artifacts and observed signals

Observed signals

Scanner coverage

Virtual patch status

Scanner Artifacts

Severity, weaknesses, and research context

All CVSS Scores

Potential Proof of Concepts

From disclosure to observed exploitation

KEV confirmed by CVE

Metasploit module available

Nessus plugin available

Added to CISA KEV

First public exploitation report

CVE published

Public PoC available

CVE ID reserved

Automate this intelligence

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