Main Vulnerability Database Vulnerabilities #VU121232

Free of Memory not on the Heap in Microsoft Windows and Windows Server - CVE-2026-20810

Published: January 13, 2026

Vulnerability identifier: #VU121232

CSH Severity: Low

CVSS v4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-20810

CWE-ID: CWE-590

Exploitation vector: Local access

Exploit availability: No public exploit available

Vulnerability details

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

The vulnerability exists due to free of memory not on the heap issue in Windows Ancillary Function Driver for WinSock. A local user can gain elevated privileges on the system.

Affected software

Microsoft Windows
Windows Server

How to mitigate CVE-2026-20810

Install updates from vendor's website.

Microsoft Windows - addressed in versions 10 21H2 10.0.19044.6809, 10 22H2 10.0.19045.6809, 10 1607 10.0.14393.8783, 10 1809 10.0.17763.8276
Windows Server - addressed in versions 2019 10.0.17763.8276, 2025 10.0.26100.7623

External References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20810

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