CVE-2026-20831
TOCTOU Race Condition in Windows WinSock Driver Elevates Privileges
Publication date: 2026-01-13
Last updated on: 2026-01-13
Assigner: Microsoft Corporation
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| microsoft | windows_ancillary_function_driver_for_winsock | * |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-367 | The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability is a time-of-check time-of-use (toctou) race condition in the Windows Ancillary Function Driver for WinSock. It allows an authorized attacker to elevate their privileges locally by exploiting the timing issue between checking a condition and using the resource. [1]
How can this vulnerability impact me? :
The vulnerability can allow an authorized attacker to elevate their privileges on the affected Windows system locally. This means the attacker could gain higher-level access than intended, potentially leading to unauthorized actions or control over the system. [1]
What immediate steps should I take to mitigate this vulnerability?
Apply the security updates provided by Microsoft for this vulnerability as soon as possible to mitigate the elevation of privilege risk caused by the toctou race condition in the Windows Ancillary Function Driver for WinSock. [1]