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Exploited· due 2022-05-038.8highHighused in ransomware

CVE-2021-34527

Microsoft Windows 10 1507

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 upd

Exploitation status

  • CISA has confirmed this is being exploited in the wild. That is an observation of real attacks, not a prediction.
  • It is known to have been used in ransomware campaigns.
  • US federal civilian agencies are required to remediate it by 2022-05-03. That deadline does not bind private companies, but it is a reasonable benchmark for how urgently CISA views it.
  • A vendor advisory or patch reference has been published.

Required action

Apply updates per vendor instructions.

CISA’s wording, unedited.

What the metrics mean

  • It is reachable over a network, without needing local access.
  • For an attacker who can reach it, no special conditions are needed to exploit it.
  • To exploit it, an ordinary user account is needed.
  • Beyond that, no action by a user is required.

Scoring

CVSS
8.8 (v3.1)
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigned by
secure@microsoft.com

Dates

Published
2021-07-02
Last modified
2026-08-10
Added to KEV
2021-11-03
Remediation due
2022-05-03
Sources
CISA KEV, NVD

Affected products

  • Microsoft Windows 10 1507- 10.0.10240.18969
  • Microsoft Windows 10 1607- 10.0.14393.4470
  • Microsoft Windows 10 1809- 10.0.17763.2029
  • Microsoft Windows 10 20h2- 10.0.19042.1083
  • Microsoft Windows 10 21h2- 10.0.19044.1415
  • Microsoft Windows 10 22h2- 10.0.19045.2251
  • Microsoft Windows 11 21h2- 10.0.22000.318
  • Microsoft Windows 11 22h2- 10.0.22621.674
  • Microsoft Windows Rt 8.1all versions
  • Microsoft Windows Server 2008all versions, r2
  • Microsoft Windows Server 2012all versions, r2
  • Microsoft Windows Server 2016- 10.0.14393.4470

As listed in the NVD configuration data. Not a statement about your estate.

References