CVE-2026-20844 is a use-after-free vulnerability (CWE-416) in the Windows Clipboard Server on Windows 10 Version 1607 (build 10.0.14393.0). Exploitation of this vulnerability allows a local attacker without privileges to elevate their privileges on the system. The vulnerability is rated high severity with a CVSS 3.1 base score of 7.4, reflecting high impact on confidentiality, integrity, and availability. Microsoft has released an official fix for this vulnerability as documented in their security update guide.

Successful exploitation of this vulnerability enables an unauthorized local attacker to elevate privileges, potentially gaining higher system rights. This can lead to full system compromise, including the ability to execute arbitrary code with elevated privileges and impact system confidentiality, integrity, and availability.

An official fix is available from Microsoft. Users and administrators should apply the security update provided by Microsoft for Windows 10 Version 1607 (build 10.0.14393.0) as soon as possible to remediate this vulnerability. Refer to the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20844 for update details and installation instructions.