CVE-2021-34527highunder attackransomware

CVE-2021-34527: high-severity vulnerability in Microsoft Windows Server 2012

Windows Print Spooler Remote Code Execution Vulnerability

Published · Updated

Follow this CVE+ Monitor Windows Server+ Monitor Windows

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

100Vexday Risk Score

Patch now. It under exploitation confirmed by CISA and has a working public exploit.

ssvc Actcvss 8.8epss 100%
from disclosure to weaponsame day
Published on NVDJul 2
1st PoCJun 29
metasploitJun 8
CISA KEV+124d
Action required by CISAfederal deadline: 2022-05-03

Apply updates per vendor instructions.

In short

The Windows Print Spooler service has a flaw that lets attackers run malicious code with the highest system privileges, potentially compromising your entire computer. This is critical because it can be exploited remotely to install malware, steal data, or create unauthorized admin accounts.

Technical detail

A remote code execution vulnerability in the Windows Print Spooler service stems from improper handling of privileged file operations. An unauthenticated attacker can exploit this remotely to execute arbitrary code with SYSTEM privileges; exploitation may be facilitated by insecure Group Policy settings (NoWarningNoElevationOnInstall=1 or UpdatePromptSettings=1).

Summary generated and translated by AI from the official description.

The full analysis of this CVE is available in Portuguese →

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:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
Affected products
Microsoft · Windows 10 Version 1507Microsoft · Windows 10 Version 1607Microsoft · Windows 10 Version 1809Microsoft · Windows 10 Version 20H2Microsoft · Windows 10 Version 21H2Microsoft · Windows 10 Version 22H2Microsoft · Windows 11 version 21H2Microsoft · Windows 11 version 22H2Microsoft · Windows 8.1Microsoft · Windows Server 2008 R2 Service Pack 1Microsoft · Windows Server 2008 R2 Service Pack 1 (Server Core installation)Microsoft · Windows Server 2008 Service Pack 2Microsoft · Windows Server 2008 Service Pack 2 (Server Core installation)Microsoft · Windows Server 2012Microsoft · Windows Server 2012 R2Microsoft · Windows Server 2012 R2 (Server Core installation)Microsoft · Windows Server 2012 (Server Core installation)Microsoft · Windows Server 2016Microsoft · Windows Server 2016 (Server Core installation)Microsoft · Windows Server 2019Microsoft · Windows Server 2019 (Server Core installation)Microsoft · Windows Server 2022Microsoft · Windows Server version 20H2
public PoCs found — 40
githubgithub.com/byt3bl33d3r/ItWasAllADream★ 801githubgithub.com/JohnHammond/CVE-2021-34527★ 318githubgithub.com/nemo-wq/PrintNightmare-CVE-2021-34527★ 173githubgithub.com/m8sec/CVE-2021-34527★ 118githubgithub.com/hackerhouse-opensource/cve-2021-34527★ 23githubgithub.com/Tomparte/PrintNightmare★ 3githubgithub.com/dywhoami/CVE-2021-34527-Scanner-Based-On-cube0x0-POC★ 3githubgithub.com/rdboboia/disable-RegisterSpoolerRemoteRpcEndPoint★ 2githubgithub.com/0xirison/PrintNightmare-Patcher★ 2githubgithub.com/powershellpr0mpt/PrintNightmare-CVE-2021-34527★ 2githubgithub.com/thomas-lauer/PrintNightmare★ 2githubgithub.com/Amaranese/CVE-2021-34527★ 1githubgithub.com/cyb3rpeace/CVE-2021-34527★ 1githubgithub.com/geekbrett/CVE-2021-34527-PrintNightmare-Workaround★ 0githubgithub.com/DenizSe/CVE-2021-34527★ 0githubgithub.com/vinaysudheer/Disable-Spooler-Service-PrintNightmare-CVE-2021-34527★ 0githubgithub.com/WidespreadPandemic/CVE-2021-34527_ACL_mitigation★ 0githubgithub.com/glorisonlai/printnightmare★ 0githubgithub.com/Eutectico/Printnightmare★ 0githubgithub.com/syntaxbearror/PowerShell-PrintNightmare★ 0githubgithub.com/fengjixuchui/CVE-2021-34527-1675★ 0githubgithub.com/d0rb/CVE-2021-34527★ 0githubgithub.com/TieuLong21Prosper/detect_bruteforce★ 0githubgithub.com/Hirusha-N/CVE-2021-34527-CVE-2023-38831-and-CVE-2023-32784★ 0githubgithub.com/AUSK1LL9/CVE-2021-34527★ 0githubgithub.com/AlDawli/CVE-2021-34527-★ 0vulncheckvulncheck.com/xdb/0544e277335eunverifiedvulncheckvulncheck.com/xdb/aafd327559cbunverifiedvulncheckvulncheck.com/xdb/5eef66f4123cunverifiedvulncheckvulncheck.com/xdb/236b4901d545unverifiedvulncheckvulncheck.com/xdb/a9a05728c824unverifiedvulncheckvulncheck.com/xdb/f06e206bb116unverifiedvulncheckvulncheck.com/xdb/66146f087766unverifiedvulncheckvulncheck.com/xdb/f4a2f262c1e1unverifiedvulncheckvulncheck.com/xdb/94dfa232ad84unverifiedcve_referencepacketstormsecurity.com/files/167261/Print-Spooler-Remote-DLL-Injection.htmlunverifiedvulncheckvulncheck.com/xdb/7383b6febefaunverifiedvulncheckvulncheck.com/xdb/de7a76d51822unverifiedvulncheckvulncheck.com/xdb/161c77693a74unverifiedvulncheckvulncheck.com/xdb/8b8ea9fe1124unverified
⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
Related CVEs — Microsoft Windows Server 2012

In the same product, most dangerous first.

CVE-2023-36884HIGHWindows Search Remote Code Execution VulnerabilityEPSS 99.4%KEVCVE-2024-21412HIGHInternet Shortcut Files Security Feature Bypass VulnerabilityEPSS 99.4%KEVCVE-2022-30190HIGHMicrosoft Windows Support Diagnostic Tool (MSDT) Remote Code Execution VulnerabilityEPSS 99.2%KEVCVE-2021-40444HIGHMicrosoft MSHTML Remote Code Execution VulnerabilityEPSS 97.8%KEVCVE-2023-36025HIGHWindows SmartScreen Security Feature Bypass VulnerabilityEPSS 88.2%KEVCVE-2025-33053HIGHInternet Shortcut Files Remote Code Execution VulnerabilityEPSS 87.1%KEV