Windows Print Spooler Remote Code Execution Vulnerability
Summary
| CVE | CVE-2021-34527 |
|---|---|
| State | PUBLISHED |
| Assigner | microsoft |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2021-07-02 22:15:08 UTC |
| Updated | 2026-08-10 20:15:22 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 8.8 HIGH from [email protected]
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.997920000 probability, percentile 0.999570000 (date 2026-08-12)
CISA KEV: Listed on 2021-11-03; due 2022-05-03; ransomware use Known
Problem Types: NVD-CWE-noinfo | Remote Code Execution | CWE-noinfo Not enough information
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | [email protected] | Secondary | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | CNA | CVSS | 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 |
| 2.0 | [email protected] | Primary | 9 | AV:N/AC:L/Au:S/C:C/I:C/A:C |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
LowUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS v2.0 Breakdown
Access Vector
NetworkAccess Complexity
LowAuthentication
SingleConfidentiality
CompleteIntegrity
CompleteAvailability
CompleteAV:N/AC:L/Au:S/C:C/I:C/A:C
CISA Known Exploited Vulnerability
| Vendor | Microsoft |
|---|---|
| Product | Windows |
| Name | Microsoft Windows Print Spooler Remote Code Execution Vulnerability |
| Required Action | Apply updates per vendor instructions. |
| Notes | Reference CISA's ED 21-04 (https://www.cisa.gov/news-events/directives/ed-21-04-mitigate-windows-print-spooler-service-vulnerability) for further guidance and requirements. Note: The due date for addressing this vulnerability aligns with the requirements outlined in ED 21-04. https://nvd.nist.gov/vuln/detail/CVE-2021-34527 |
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Operating System | Microsoft | Windows 10 1507 | All | All | All | All |
| Operating System | Microsoft | Windows 10 1607 | All | All | All | All |
| Operating System | Microsoft | Windows 10 1809 | All | All | All | All |
| Operating System | Microsoft | Windows 10 20h2 | All | All | All | All |
| Operating System | Microsoft | Windows 10 21h2 | All | All | All | All |
| Operating System | Microsoft | Windows 10 22h2 | All | All | All | All |
| Operating System | Microsoft | Windows 11 21h2 | All | All | All | All |
| Operating System | Microsoft | Windows 11 22h2 | All | All | All | All |
| Operating System | Microsoft | Windows Rt 8.1 | - | All | All | All |
| Operating System | Microsoft | Windows Server 2008 | - | sp2 | All | All |
| Operating System | Microsoft | Windows Server 2008 | r2 | sp1 | All | All |
| Operating System | Microsoft | Windows Server 2012 | - | All | All | All |
| Operating System | Microsoft | Windows Server 2012 | r2 | All | All | All |
| Operating System | Microsoft | Windows Server 2016 | All | All | All | All |
| Operating System | Microsoft | Windows Server 2019 | All | All | All | All |
| Operating System | Microsoft | Windows Server 2022 | All | All | All | All |
| Operating System | Microsoft | Windows Server 20h2 | All | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Microsoft | Windows 10 Version 1507 | affected 10.0.10240.0 10.0.10240.18969 custom | 32-bit Systems, x64-based Systems |
| CNA | Microsoft | Windows 10 Version 1607 | affected 10.0.14393.0 10.0.14393.4470 custom | 32-bit Systems, x64-based Systems |
| CNA | Microsoft | Windows 10 Version 1809 | affected 10.0.17763.0 10.0.17763.2029 custom | 32-bit Systems, x64-based Systems |
| CNA | Microsoft | Windows 10 Version 1809 | affected 10.0.0 10.0.17763.2029 custom | ARM64-based Systems |
| CNA | Microsoft | Windows 10 Version 20H2 | affected 10.0.0 10.0.19042.1083 custom | 32-bit Systems, ARM64-based Systems |
| CNA | Microsoft | Windows 10 Version 21H2 | affected 10.0.19044.0 10.0.19044.1415 custom | 32-bit Systems, ARM64-based Systems, x64-based Systems |
| CNA | Microsoft | Windows 10 Version 22H2 | affected 10.0.19045.0 10.0.19045.2251 custom | 32-bit Systems, ARM64-based Systems, x64-based Systems |
| CNA | Microsoft | Windows 11 Version 21H2 | affected 10.0.22000.0 10.0.22000.318 custom | ARM64-based Systems, x64-based Systems |
| CNA | Microsoft | Windows 11 Version 22H2 | affected 10.0.22621.0 10.0.22621.674 custom | ARM64-based Systems, x64-based Systems |
| CNA | Microsoft | Windows 8.1 | affected 6.3.0 6.3.9600.20046 custom | ARM64-based Systems |
| CNA | Microsoft | Windows Server 2008 R2 Service Pack 1 | affected 6.1.7601.0 6.1.7601.25633 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2008 R2 Service Pack 1 Server Core Installation | affected 6.1.7601.0 6.1.7601.25633 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2008 Service Pack 2 | affected 6.0.6003.0 6.0.6003.21138 custom | 32-bit Systems, x64-based Systems |
| CNA | Microsoft | Windows Server 2008 Service Pack 2 Server Core Installation | affected 6.0.6003.0 6.0.6003.21138 custom | 32-bit Systems, x64-based Systems |
| CNA | Microsoft | Windows Server 2012 | affected 6.2.9200.0 6.2.9200.23383 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2012 Server Core Installation | affected 6.2.9200.0 6.2.9200.23383 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2012 R2 | affected 6.3.9600.0 6.3.9600.20046 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2012 R2 Server Core Installation | affected 6.3.9600.0 6.3.9600.20046 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2016 | affected 10.0.14393.0 10.0.14393.4470 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2016 Server Core Installation | affected 10.0.14393.0 10.0.14393.4470 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2019 | affected 10.0.17763.0 10.0.17763.2029 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2019 Server Core Installation | affected 10.0.17763.0 10.0.17763.2029 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2022 | affected 10.0.20348.0 10.0.20348.230 custom | x64-based Systems |
| CNA | Microsoft | Windows Server Version 20H2 | affected 10.0.0 10.0.19042.1083 custom | x64-based Systems |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| Print Spooler Remote DLL Injection ≈ Packet Storm | af854a3a-2127-422b-91ae-364da2661108 | packetstormsecurity.com | Exploit, Third Party Advisory, VDB Entry |
| www.cisa.gov/known-exploited-vulnerabilities-catalog | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | www.cisa.gov | US Government Resource |
| www.vicarius.io/vsociety/posts/cve-2021-34527-printnightmare-mitigation-script | af854a3a-2127-422b-91ae-364da2661108 | www.vicarius.io | Exploit, Third Party Advisory |
| VU#383432 - Microsoft Windows Print Spooler allows for RCE via AddPrinterDriverEx() | af854a3a-2127-422b-91ae-364da2661108 | www.kb.cert.org | Third Party Advisory, US Government Resource |
| www.vicarius.io/vsociety/posts/cve-2021-34527-printnightmare-detection-script | af854a3a-2127-422b-91ae-364da2661108 | www.vicarius.io | Exploit, Third Party Advisory |
| Security Update Guide - Microsoft Security Response Center | af854a3a-2127-422b-91ae-364da2661108 | portal.msrc.microsoft.com | Mitigation, Patch, Vendor Advisory |
| msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34527 | [email protected] | msrc.microsoft.com | Patch, Vendor Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
| CISA Known Exploited Vulnerabilities catalog | CISA | www.cisa.gov | kev |
No vendor comments have been submitted for this CVE.
Legacy QID Mappings
- 91785 Microsoft Windows Print Spooler Remote Code Execution Vulnerability (PrintNightmare)