CVE-2026-20831: CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition in Microsoft Windows 10 Version 1607
Time-of-check time-of-use (toctou) race condition in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
AI Analysis
Technical Summary
This vulnerability is a TOCTOU race condition in the Windows Ancillary Function Driver for WinSock on Windows 10 Version 1607 (build 10.0.14393.0). It allows an attacker with local authorized access to exploit the timing discrepancy between checking a condition and using a resource, resulting in privilege escalation. The CVSS v3.1 base score is 7.8, indicating high severity with high impact on confidentiality, integrity, and availability. Microsoft has released an official fix for this vulnerability.
Potential Impact
An authorized local attacker can exploit this race condition to elevate privileges on the affected system, potentially gaining higher-level access than intended. This can lead to full system compromise, including unauthorized access to sensitive data and system control.
Mitigation Recommendations
Microsoft has released an official fix for this vulnerability. Users and administrators should apply the security update provided by Microsoft as soon as possible to remediate this issue. No additional mitigation steps are indicated beyond applying the official patch.
CVE-2026-20831: CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition in Microsoft Windows 10 Version 1607
Description
Time-of-check time-of-use (toctou) race condition in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
CVSS v3.1
Score 7.8high
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability is a TOCTOU race condition in the Windows Ancillary Function Driver for WinSock on Windows 10 Version 1607 (build 10.0.14393.0). It allows an attacker with local authorized access to exploit the timing discrepancy between checking a condition and using a resource, resulting in privilege escalation. The CVSS v3.1 base score is 7.8, indicating high severity with high impact on confidentiality, integrity, and availability. Microsoft has released an official fix for this vulnerability.
Potential Impact
An authorized local attacker can exploit this race condition to elevate privileges on the affected system, potentially gaining higher-level access than intended. This can lead to full system compromise, including unauthorized access to sensitive data and system control.
Mitigation Recommendations
Microsoft has released an official fix for this vulnerability. Users and administrators should apply the security update provided by Microsoft as soon as possible to remediate this issue. No additional mitigation steps are indicated beyond applying the official patch.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- microsoft
- Date Reserved
- 2025-12-03T05:54:20.375Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- official-fix
- Vendor Advisory Urls
- [{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20831","vendor":"Microsoft"}]
Threat ID: 69668adda60475309f9adfea
Added to database: 01/13/2026, 18:11:41 UTC
Last enriched: 07/30/2026, 23:47:54 UTC
Last updated: 09/10/2026, 19:36:52 UTC
Views: 188
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