PT-2026-40164 · Microsoft · Windows Ancillary Function Driver For Winsock+1

Published 2026-05-12 · Updated 2026-05-12 · CVE-2026-34345

Positive Technologies (AI Summary)

CVSS v3.1

7.0

High

Base vector

AV:L/AC:H/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 race condition occurs in the Windows Ancillary Function Driver for WinSock due to improper synchronization when using a shared resource. This allows an authorized local attacker to elevate their privileges to SYSTEM level.

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

LPE

Race Condition

Use After Free

Weakness Enumeration

CWE-362

CWE-416

Related Identifiers

BDU:2026-06604

CVE-2026-34345

Affected Products

Windows

Windows Ancillary Function Driver For Winsock

References · 8

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-34345 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-34345 · Security Note
• http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-34345 · Security Note
• https://bdu.fstec.ru/vul/2026-06604 · Security Note
• https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2026-34345 · Vendor Advisory
• https://twitter.com/threatcluster/status/2054260707265290400 · Twitter Post
• https://feedly.com/cve/CVE-2026-34345 · Note
• https://twitter.com/windowsforum/status/2054267926627115373 · Twitter Post