CVE-2026-20810
Published: 13 January 2026
Summary
CVE-2026-20810 is a high-severity Free of Memory not on the Heap (CWE-590) vulnerability in Microsoft Windows 10 1809. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 11.3th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-16 (Memory Protection) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-20810 is a vulnerability in the Windows Ancillary Function Driver for WinSock involving a free of memory not on the heap, classified under CWE-590. Published on 2026-01-13, it carries a CVSS v3.1 base score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) and affects Windows systems utilizing this driver.
A local attacker with low privileges can exploit the vulnerability due to its low attack complexity and lack of required user interaction. Successful exploitation enables privilege escalation, resulting in high impacts to confidentiality, integrity, and availability.
Microsoft's update guide provides details on mitigation and patches at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20810.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-2194
Vulnerability details
Free of memory not on the heap in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Local kernel driver vulnerability (WinSock AFDS) directly enables privilege escalation from low-privileged context.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly mitigates the memory management flaw in the Windows Ancillary Function Driver for WinSock by requiring timely patching and flaw remediation.
Implements memory protection mechanisms such as DEP and ASLR to prevent exploitation of invalid memory frees leading to local privilege escalation.
Enforces least privilege on processes and users to limit the attack surface and impact of privilege escalation from low-privileged local attackers.