CVE-2026-20926
Published: 13 January 2026
Summary
CVE-2026-20926 is a high-severity Race Condition (CWE-362) vulnerability in Microsoft Windows 10 1607. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 9.8th 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 SC-4 (Information in Shared System Resources) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-20926 is a race condition vulnerability (CWE-362) in the Windows SMB Server, caused by concurrent execution using a shared resource with improper synchronization. Published on 2026-01-13T18:16:19.423, it carries a CVSS v3.1 base score of 7.5 (AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H) and affects the Windows SMB Server component.
An authorized attacker with low privileges (PR:L) can exploit this vulnerability over the network (AV:N) despite high attack complexity (AC:H) and no required user interaction (UI:N). Successful exploitation enables privilege escalation, resulting in high impacts to confidentiality, integrity, and availability (C:H/I:H/A:H) within an unchanged scope (S:U).
Microsoft's update guide provides details on mitigation and patching for CVE-2026-20926, available at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20926.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-2141
Vulnerability details
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate privileges over a network.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Race condition in SMB Server directly enables remote exploitation for privilege escalation by a low-privileged attacker.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly mitigates the race condition vulnerability by requiring timely application of vendor patches for the Windows SMB Server flaw.
Prevents unauthorized access or state corruption via shared system resources, directly addressing the improper synchronization in concurrent SMB operations.
Limits the scope and impact of privilege escalation by enforcing least privilege on accounts and processes interacting with the SMB server.