CVE-2021-34527
Microsoft Windows Print Spooler Remote Code Execution Vulnerability
IN CISA KEV
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 h…
- Vendor
- Microsoft
- Product
- Windows
- CVSS 3.1
- 8.8 (high), scored by secure@microsoft.comCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CVSS 3.1
- 8.8 (high), scored by NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CWE
- CWE-269
- Published
- 2021-07-02
- NVD modified
- 2026-08-10
- NVD status
- Analyzed
CISA KEV
- Date added
- 2021-11-03
- Due date
- 2022-05-03
- Ransomware use
- Known
- Required action
- Apply updates per vendor instructions.
EPSS
100% chance of exploitation in the next 30 days (percentile 99th)
FIRST EPSS, updated 17 Oct 2026. About EPSS
CVSS is severity, EPSS is likelihood, KEV means already exploited. EPSS is a statistical probability, not a certainty: a low score does not make a bug safe, and a high one does not prove it is being exploited.
References
- msrc.microsoft.com (Patch, Vendor Advisory)
- portal.msrc.microsoft.com (Mitigation, Patch, Vendor Advisory)
- www.kb.cert.org (Third Party Advisory, US Government Resource)
- www.cisa.gov (US Government Resource)
Data last updated 18 Oct 2026. Sources: NVD API 2.0, CISA KEV catalog, FIRST EPSS. Links: NVD, CISA KEV. Metadata only. ThreatWire does not host exploit code.