PT-2026-2681 · Microsoft · Windows Ancillary Function Driver For Winsock+1

Angelboy + 5 · Published 2026-01-13 · Updated 2026-01-17 · CVE-2026-20831

Positive Technologies (AI Summary)

CVSS v3.1

7.8

High

Base vector

AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Name of the Vulnerable Software and Affected Versions Windows Ancillary Function Driver for WinSock (affected versions not specified)

Description A time-of-check time-of-use (TOCTOU) race condition exists in the Windows Ancillary Function Driver for WinSock. This condition allows a locally authorized attacker to elevate privileges. The issue arises from a timing window where a check is performed, and the state changes before the operation is carried out, potentially leading to unintended consequences.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Time Of Check To Time Of Use

Weakness Enumeration

CWE-367

Related Identifiers

BDU:2026-00486

CVE-2026-20831

Affected Products

Windows

Windows Ancillary Function Driver For Winsock

References · 7

• https://nvd.nist.gov/vuln/detail/CVE-2026-20831 · Security Note
• https://bdu.fstec.ru/vul/2026-00486 · Security Note
• https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2026-20831 · Vendor Advisory
• http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-20831 · Security Note
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20831 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2026-20831 · Vendor Advisory
• https://twitter.com/CVEnew/status/2012490411848126555 · Twitter Post