Advisory Details

January 13th, 2026

Microsoft Windows Desktop Window Manager Use-After-Free Local Privilege Escalation Vulnerability

ZDI-26-044
ZDI-CAN-28082

CVE ID CVE-2026-20871
CVSS SCORE 7.8, AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
AFFECTED VENDORS Microsoft
AFFECTED PRODUCTS Windows
VULNERABILITY DETAILS

This vulnerability allows local attackers to escalate privileges on affected installations of Microsoft Windows. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

The specific flaw exists within the desktop window manager component. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of SYSTEM.

ADDITIONAL DETAILS Microsoft has issued an update to correct this vulnerability. More details can be found at:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20871
DISCLOSURE TIMELINE
  • 2025-10-10 - Vulnerability reported to vendor
  • 2026-01-13 - Coordinated public release of advisory
  • 2026-01-13 - Advisory Updated
CREDIT Anonymous
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