7.8High

Microsoft Windows 10

CVE-2021-38639

Win32k Elevation of Privilege Vulnerability

What this means for your business

  • It affects Microsoft Windows 10. It matters if your company, or a supplier that handles your data, runs it.
  • An attacker can use it only with access to the machine itself, with an ordinary user login, and without anyone at your company clicking anything.
  • FIRST's prediction model gives it a 1% chance of attack attempts being seen in the next 30 days, ranking above 69% of all known flaws.

What to do

  1. 1Check whether your company or your suppliers run Microsoft Windows 10, and which version. The affected versions are listed further down this page.
  2. 2If you do, apply the vendor's fix. A patch or vendor advisory has been published.

Not sure if your company is exposed?

Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.

Scoring

CVSS
7.8 (v3.1)
Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-269
Assigned by
secure@microsoft.com

Dates

Published
2021-09-15
Last modified
2026-08-10
Sources
NVD

Affected products

  • Microsoft Windows 10all versions, 20h2, 21h1, 1607, 1809, 1909, 2004
  • Microsoft Windows 7all versions
  • Microsoft Windows 8.1all versions
  • Microsoft Windows Rt 8.1all versions
  • Microsoft Windows Server 2008all versions, r2
  • Microsoft Windows Server 2012all versions
  • Microsoft Windows Server 2016all versions, 20h2, 2004
  • Microsoft Windows Server 2019all versions
  • Microsoft Windows Server 2022all versions

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

References