Zero-day vulnerability in Windows

Type Confusion
CVE-2026-21519

Vulnerability details

Advisory: SB2026021064 - Privilege escalation in Microsoft Desktop Window Manager

Vulnerable component: Windows

CVE-ID: CVE-2026-21519

CVSSv3 score: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C

CWE-ID: CWE-843 - Type confusion

Description:

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a type confusion error in Desktop Window Manager. A local user can trigger a type confusion error and execute arbitrary code on the target system.

Note, the vulnerability is being actively exploited in the wild. 

External links:

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21519


About zero-day vulnerabilities

Zero-day vulnerability is an undisclosed vulnerability in software that hackers can exploit to compromise computer programs, gain unauthorized access to sensitive data, penetrate networks, etc. We consider vulnerability a zero-day when there is no solution provided from software vendor and the vulnerability is being actively exploited by malicious actors.

Zero-day candidate is a potential zero-day vulnerability in software which might have been used in targeted attacks, however there is no evidence to support this suggestion.