CVE-2021-34527

8.8 HIGH CISA KEV - Actively Exploited
Published: July 02, 2021 Modified: November 06, 2025

Description

<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>

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
http://packetstormsecurity.com/files/167261/Print-Spooler-Remote-DLL-Injection.html
Source: secure@microsoft.com
Exploit Third Party Advisory VDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34527
Source: secure@microsoft.com
Mitigation Patch Vendor Advisory
http://packetstormsecurity.com/files/167261/Print-Spooler-Remote-DLL-Injection.html
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Third Party Advisory VDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34527
Source: af854a3a-2127-422b-91ae-364da2661108
Mitigation Patch Vendor Advisory
https://www.kb.cert.org/vuls/id/383432
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory US Government Resource
https://www.vicarius.io/vsociety/posts/cve-2021-34527-printnightmare-detection-script
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Third Party Advisory
https://www.vicarius.io/vsociety/posts/cve-2021-34527-printnightmare-mitigation-script
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34527
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
US Government Resource

8 reference(s) from NVD

Quick Stats

CVSS v3 Score
8.8 / 10.0
EPSS (Exploit Probability)
94.3%
100th percentile
Exploitation Status
Actively Exploited
Remediation due: 2022-05-03

Affected Vendors

microsoft