CVE-2021-34527 Microsoft Windows Print Spooler Remote Code Execution
Attackers can execute arbitrary code with SYSTEM privileges via the Windows Print Spooler service, requiring immediate patching.
- Exploited in the wild
- Since 3 Nov 2021
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-34527?
CVE-2021-34527 is a high-severity vulnerability in Microsoft Windows 10 1507, published on 2 Jul 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2021-34527?
It affects 15 products.
Products include Microsoft Windows 10 1507, Microsoft Windows 10 1607, Microsoft Windows 10 1809, Microsoft Windows 10 20h2, Microsoft Windows 10 21h2, Microsoft Windows 10 22h2 and 9 more.
How do I fix CVE-2021-34527?
No fix has been published for CVE-2021-34527 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 3 May 2022.
Is CVE-2021-34527 being exploited?
Yes. Attackers have exploited CVE-2021-34527 in the wild since at least 3 Nov 2021, including in ransomware campaigns.
Public exploit code: 1 Metasploit module and 30 proofs of concept on GitHub.
Other vulnerabilities in Microsoft Windows 10 1507
- CVE-2017-8543 Microsoft Windows Search Remote Code Execution
- CVE-2025-33053 Microsoft Windows External Control of File Name or Path
- CVE-2025-33073 Microsoft Windows SMB Client Improper Access Control
- CVE-2024-49039 Microsoft Windows Task Scheduler Privilege Escalation
- CVE-2024-43461 Microsoft Windows MSHTML Platform Spoofing
Sources
Also known as GHSA-75f9-mm5v-2rgm.