CVE-2026-20860
Published: 13 January 2026
Summary
CVE-2026-20860 is a high-severity Type Confusion (CWE-843) vulnerability in Microsoft Windows Server 2008. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 44.5% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-2 (Flaw Remediation) and AC-6 (Least Privilege).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Directly mitigates the type confusion vulnerability by requiring timely installation of vendor patches for the affected Windows Ancillary Function Driver.
Implements memory protection mechanisms such as ASLR and DEP that hinder exploitation of type confusion leading to privilege escalation.
Enforces least privilege to restrict the scope and impact of local privilege escalation even if the vulnerability is exploited.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Local type confusion vulnerability in a Windows kernel driver directly enables exploitation for privilege escalation from low to high privileges.
NVD Description
Access of resource using incompatible type ('type confusion') in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
Deeper analysisAI
CVE-2026-20860 is a type confusion vulnerability, classified under CWE-843 (Access of Resource Using Incompatible Type), affecting the Windows Ancillary Function Driver for WinSock. Published on 2026-01-13, it enables an authorized attacker to elevate privileges locally by accessing a resource with an incompatible type. The vulnerability 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), indicating high severity due to its potential for significant impact.
A local attacker with low privileges (PR:L) can exploit this vulnerability with low attack complexity and no user interaction required. Successful exploitation allows privilege escalation, granting high levels of access to confidentiality, integrity, and availability of the system.
Microsoft's Security Response Center (MSRC) provides guidance on mitigation and patching in its update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20860.
Details
- CWE(s)