CVE-2021-34527
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
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.
- Record
CVE-2021-34527- CVSS 3.1
- 8.8 High
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 - Updated
- 2026-11-02
EUVDEUVD-2021-21181
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.
- Record
EUVD-2021-21181- CVSS 3.1
- 8.8 High
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-75f9-mm5v-2rgm
Windows Print Spooler Remote Code Execution Vulnerability
Windows Print Spooler Remote Code Execution Vulnerability
- Record
GHSA-75f9-mm5v-2rgm- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-269
- Updated
- 2026-11-02
CISA KEV No score
Microsoft Windows Print Spooler Remote Code Execution Vulnerability
Microsoft Windows Print Spooler contains an unspecified vulnerability due to the Windows Print Spooler service improperly performing privileged file operations. Successful exploitation allows an attacker to perform remote code execution with SYSTEM privileges. The vulnerability is also known under the moniker of PrintNightmare.
- Record
CVE-2021-34527- Weakness
- CWE-269
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2021-34527- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 9.0 High
AV:N/AC:L/Au:S/C:C/I:C/A:C - Updated
- 2026-11-02
Affected products
- microsoft windows
- microsoft windows server 2012
- microsoft windows server 2016
- microsoft windows 10 version 1507
- microsoft windows 10 version 1607
- microsoft windows 10 version 1809
- microsoft windows 10 version 20h2
- microsoft windows 10 version 21h2
- microsoft windows 10 version 22h2
- microsoft windows 11 version 21h2
- microsoft windows 11 version 22h2
- microsoft windows 8.1
Show 23 moreShow less
- microsoft windows server 2008 r2 service pack 1
- microsoft windows server 2008 r2 service pack 1 (server core installation)
- microsoft windows server 2008 service pack 2
- microsoft windows server 2008 service pack 2 (server core installation)
- microsoft windows server 2012 (server core installation)
- microsoft windows server 2012 r2
- microsoft windows server 2012 r2 (server core installation)
- microsoft windows server 2016 (server core installation)
- microsoft windows server 2019
- microsoft windows server 2019 (server core installation)
- microsoft windows server 2022
- microsoft windows server version 20h2
- microsoft windows 10 1507
- microsoft windows 10 1607
- microsoft windows 10 1809
- microsoft windows 10 20h2
- microsoft windows 10 21h2
- microsoft windows 10 22h2
- microsoft windows 11 21h2
- microsoft windows 11 22h2
- microsoft windows rt 8.1
- microsoft windows server 2008
- microsoft windows server 20h2
Public exploits
Links only. Every CVE stores no exploit code.
| Source | Link | Date |
|---|---|---|
| Metasploit | Print Spooler Remote DLL Injection | 2021-06-08 |
| PoC in GitHub | DenizSe/CVE-2021-34527 | 2021-07-01 |
| PoC in GitHub | JohnHammond/CVE-2021-34527 | 2021-07-02 |
| PoC in GitHub | nemo-wq/PrintNightmare-CVE-2021-34527 | 2021-07-03 |
| PoC in GitHub | twi1ight00/PrintNightmare | 2021-07-03 |
| PoC in GitHub | byt3bl33d3r/ItWasAllADream | 2021-07-05 |
| PoC in GitHub | geekbrett/CVE-2021-34527-PrintNightmare-Workaround | 2021-07-05 |
| PoC in GitHub | rdboboia/disable-RegisterSpoolerRemoteRpcEndPoint | 2021-07-05 |
| PoC in GitHub | powershellpr0mpt/PrintNightmare-CVE-2021-34527 | 2021-07-07 |
| PoC in GitHub | vinaysudheer/Disable-Spooler-Service-PrintNightmare-CVE-2021-34527 | 2021-07-07 |
Show 16 moreShow less
| Source | Link | Date |
|---|---|---|
| PoC in GitHub | WidespreadPandemic/CVE-2021-34527_ACL_mitigation | 2021-07-08 |
| PoC in GitHub | glorisonlai/printnightmare | 2021-07-08 |
| PoC in GitHub | Eutectico/Printnightmare | 2021-07-09 |
| PoC in GitHub | dywhoami/CVE-2021-34527-Scanner-Based-On-cube0x0-POC | 2021-07-09 |
| PoC in GitHub | syntaxbearror/PowerShell-PrintNightmare | 2021-07-09 |
| PoC in GitHub | 0xirison/PrintNightmare-Patcher | 2021-07-12 |
| PoC in GitHub | fengjixuchui/CVE-2021-34527-1675 | 2021-07-13 |
| PoC in GitHub | Tomparte/PrintNightmare | 2021-07-28 |
| PoC in GitHub | Amaranese/CVE-2021-34527 | 2021-12-13 |
| PoC in GitHub | cyb3rpeace/CVE-2021-34527 | 2022-06-24 |
| PoC in GitHub | m8sec/CVE-2021-34527 | 2022-08-23 |
| PoC in GitHub | hackerhouse-opensource/cve-2021-34527 | 2022-09-05 |
| PoC in GitHub | d0rb/CVE-2021-34527 | 2023-08-20 |
| PoC in GitHub | TieuLong21Prosper/detect_bruteforce | 2023-10-28 |
| PoC in GitHub | Hirusha-N/CVE-2021-34527-CVE-2023-38831-and-CVE-2023-32784 | 2024-06-25 |
| PoC in GitHub | AUSK1LL9/CVE-2021-34527 | 2025-05-21 |
Plus 5 more. The full list has every link.
History
| Recorded | Changed | Sources |
|---|---|---|
| exploitation | ||
| exploits, exploits_more | ||
| first indexed | CVE List, EUVD, GitHub Advisories, CISA KEV, Metasploit, NVD, PoC in GitHub |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-34527 is a high vulnerability (CVSS 8.8) in Microsoft Windows, published July 2, 2021. CISA lists it as known to be exploited, since November 3, 2021. EUVD reports exploitation since November 3, 2021. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 99.8%, the 99th percentile. No source names a fixed version.
References
msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34527
cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34527
vicarius.io/vsociety/posts/cve-2021-34527-printnightmare-detection-script
portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34527
packetstormsecurity.com/files/167261/Print-Spooler-Remote-DLL-Injection.html
kb.cert.org/vuls/id/383432
nvd.nist.gov/vuln/detail/CVE-2021-34527
github.com/advisories/GHSA-75f9-mm5v-2rgm