PT-2026-7340 · Microsoft · Windows Ancillary Function Driver For Winsock+1

CVE-2026-21236 · Published 2026-02-10 · Updated 2026-06-22

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 An elevation-of-privilege issue exists in the Windows Ancillary Function Driver for WinSock, potentially allowing an attacker to elevate privileges locally. The issue is related to a heap-based buffer overflow in the driver's dynamic memory allocation. Exploitation may allow an attacker to gain higher privileges within the system.

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

DoS

LPE

Heap Based Buffer Overflow

Memory Corruption

Weakness Enumeration

CWE-122

CWE-787

Related Identifiers

BDU:2026-01778

CVE-2026-21236

Affected Products

Windows

Windows Ancillary Function Driver For Winsock

References · 15

• https://osv.dev/vulnerability/CVE-2026-21236 · Vendor Advisory
• https://bdu.fstec.ru/vul/2026-01778 · Security Note
• http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-21236 · Security Note
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21236 · Vendor Advisory
• https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2026-21236 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-21236 · Security Note
• https://twitter.com/alexjplaskett/status/2069073305135456341 · Twitter Post
• https://twitter.com/DarkWebInformer/status/2034359036196372698 · Twitter Post
• https://twitter.com/vuln_tracker/status/2034578815893094596 · Twitter Post
• https://t.me/avleonovcom/1631 · Telegram Post
• https://twitter.com/alexjplaskett/status/2033961972014719484 · Twitter Post
• https://twitter.com/vuln_tracker/status/2034147299702804842 · Twitter Post
• https://twitter.com/alpagu995/status/2034364286529651106 · Twitter Post
• https://twitter.com/_patchpoint_/status/2028643669063131447 · Twitter Post
• https://twitter.com/NullSecurityX/status/2040527631469142490 · Twitter Post