CVE-2021-34527 — Windows Print Spooler Remote Code Execution Vulnerability

Executive Summary

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.

Overview

8.8

CVSS HIGH

Critical

MS Severity

Exploited

MS Exploit Status

Exploitation Detected

MS Exploit Likelihood

Category Remote Code Execution

Released Jul 13 2021

Last Updated Jul 13 2021

Publicly Disclosed Yes

CISA KEV Not Listed

Known Exploits None Known

NVD CVSS 8.8 HIGH — matches MSRC

CVSS 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

ATTACK VECTOR

Network

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

Low

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

High

INTEGRITY

High

AVAILABILITY

High

EXPLOIT CODE MATURITY

Functional

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 8.2

EPSS Score

No EPSS score available for this CVE.

View on FIRST.org

Affected Products

47 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1809 for 32-bit Systems	`5004947 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1809 for x64-based Systems	`5004947 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1809 for ARM64-based Systems	`5004947 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2019	`5004947 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2019 (Server Core installation)	`5004947 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2022	`5005575 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2022 (Server Core installation)	`5005575 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 20H2 for 32-bit Systems	`5004945 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 20H2 for ARM64-based Systems	`5004945 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server, version 20H2 (Server Core Installation)	`5004945 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 version 21H2 for x64-based Systems	`5007215 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 version 21H2 for ARM64-based Systems	`5007215 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H2 for 32-bit Systems	`5008212 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H2 for ARM64-based Systems	`5008212 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H2 for x64-based Systems	`5008212 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 22H2 for ARM64-based Systems	`5018427 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 22H2 for x64-based Systems	`5018427 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 22H2 for x64-based Systems	`5019959 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 22H2 for ARM64-based Systems	`5019959 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 22H2 for 32-bit Systems	`5019959 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 for 32-bit Systems	`5004950 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 for x64-based Systems	`5004950 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1607 for 32-bit Systems	`5004948 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1607 for x64-based Systems	`5004948 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2016	`5004948 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2016 (Server Core installation)	`5004948 (Security Update)`	Critical	Remote Code Execution	Yes
Windows RT 8.1	`5004954 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2008 for 32-bit Systems Service Pack 2	`5004955 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)	`5004955 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2008 for x64-based Systems Service Pack 2	`5004955 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)	`5004955 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2008 for 32-bit Systems Service Pack 2	`5004959 (Security Only)`	Critical	Remote Code Execution	Yes
Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)	`5004959 (Security Only)`	Critical	Remote Code Execution	Yes
Windows Server 2008 for x64-based Systems Service Pack 2	`5004959 (Security Only)`	Critical	Remote Code Execution	Yes
Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)	`5004959 (Security Only)`	Critical	Remote Code Execution	Yes
Windows Server 2008 R2 for x64-based Systems Service Pack 1	`5004953 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)	`5004953 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2008 R2 for x64-based Systems Service Pack 1	`5004951 (Security Only)`	Critical	Remote Code Execution	Yes
Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)	`5004951 (Security Only)`	Critical	Remote Code Execution	Yes
Windows Server 2012	`5004956 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2012 (Server Core installation)	`5004956 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2012	`5004960 (Security Only)`	Critical	Remote Code Execution	Yes
Windows Server 2012 (Server Core installation)	`5004960 (Security Only)`	Critical	Remote Code Execution	Yes
Windows Server 2012 R2	`5004954 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2012 R2 (Server Core installation)	`5004954 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2012 R2	`5004958 (Security Only)`	Critical	Remote Code Execution	Yes
Windows Server 2012 R2 (Server Core installation)	`5004958 (Security Only)`	Critical	Remote Code Execution	Yes

Patches

17 patches

Article	Type	Restart
`5004947`	Security Update	Yes
`5005575`	Security Update	Yes
`5004945`	Security Update	Yes
`5007215`	Security Update	Yes
`5008212`	Security Update	Yes
`5018427`	Security Update	Yes
`5019959`	Security Update	Yes
`5004950`	Security Update	Yes
`5004948`	Security Update	Yes
`5004954`	Monthly Rollup	Yes
`5004955`	Monthly Rollup	Yes
`5004959`	Security Only	Yes
`5004953`	Monthly Rollup	Yes
`5004951`	Security Only	Yes
`5004956`	Monthly Rollup	Yes
`5004960`	Security Only	Yes
`5004958`	Security Only	Yes

Known Exploits

No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.

Acknowledgments

Zhiniang Peng (@edwardzpeng) and Xuefeng Li (@lxf02942370); Sergii Bezus with 10Guards

References

MSRC Advisory MITRE NVD