CVE-2026-21519: Microsoft Windows type confusion in Desktop Window Manager

CVE-2026-21519 · Severity: critical · CVSS 7.8 · Exploited in the wild · Published 2026-02-10

A vulnerability exists in the Microsoft Desktop Window Manager, the component responsible for rendering the visual interface of the Windows operating system. An attacker who already has basic access to a system could exploit this flaw to gain full administrative control. This could allow them to bypass security restrictions, access sensitive data, or install malicious software. This vulnerability is reportedly being actively exploited in the wild.

Technologies: Microsoft Windows. Vendors: Microsoft.

Quick answers

Is CVE-2026-21519 exploited in the wild?
Yes. CVE-2026-21519 is known to be exploited in the wild, first recorded on 10 February 2026. Treat it as urgent.
How severe is CVE-2026-21519?
Critical severity, with a CVSS score of 7.8, published 10 February 2026.
Which products and versions are affected?
Microsoft Windows 10 1607, 1809, 21H2, 22H2; Microsoft Windows 11 23H2, 24H2, 25H2; Microsoft Windows Server 2016, 2019, 2022, 2025, 23H2.
Is there a fix for CVE-2026-21519?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-21519 attacked?
It is attacked with local access, in an operating system.
Am I affected by CVE-2026-21519?
Check whether you run Microsoft Windows. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A type confusion vulnerability (CWE-843) exists in the Microsoft Desktop Window Manager (DWM). The flaw stems from the DWM improperly handling resources of incompatible types, which can be manipulated by a local attacker with low privileges. By successfully exploiting this vulnerability, an attacker can achieve local privilege escalation (LPE), potentially gaining SYSTEM-level access. The attack requires local authentication but no user interaction. Microsoft has released patches for various versions of Windows 10, 11, and Windows Server to address this issue. This vulnerability has been added to the CISA Known Exploited Vulnerabilities (KEV) catalog.

Affected products

  • Microsoft Windows 10 1607, 1809, 21H2, 22H2
  • Microsoft Windows 11 23H2, 24H2, 25H2
  • Microsoft Windows Server 2016, 2019, 2022, 2025, 23H2

Timeline

  • 2026-02-10: disclosed: Initial disclosure by Microsoft
  • 2026-02-10: advisory: Microsoft released vendor advisory MSRC CVE-2026-21519
  • 2026-02-10: kev added: CISA added the vulnerability to the Known Exploited Vulnerabilities catalog
  • 2026-02-10: exploited: Vulnerability reported as exploited in the wild at time of disclosure

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