PT-2026-7345 · Microsoft · Windows Ancillary Function Driver For Winsock+1

Dark_Puzzle + 1 · Published 2026-02-10 · Updated 2026-06-15 · CVE-2026-21241

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 versions (affected versions not specified)

Description A use-after-free condition exists in the Windows Ancillary Function Driver for WinSock, specifically within the afd.sys file. This issue allows an authorized attacker to elevate privileges locally. The vulnerability is related to memory management and occurs when memory is accessed after it has been freed. Exploitation of this issue can allow an attacker to affect the system. Research indicates the vulnerability was discovered through exploration of Windows I/O completion internals.

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

DoS

LPE

Use After Free

Weakness Enumeration

CWE-416

Related Identifiers

BDU:2026-01803

CVE-2026-21241

Affected Products

Windows

Windows Ancillary Function Driver For Winsock

References · 11

• https://osv.dev/vulnerability/CVE-2026-21241 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-21241 · Security Note
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21241 · Vendor Advisory
• http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-21241 · Security Note
• https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2026-21241 · Vendor Advisory
• https://bdu.fstec.ru/vul/2026-01803 · Security Note
• https://twitter.com/Dinosn/status/2025064952201965906 · Twitter Post
• https://twitter.com/hackyboiz2/status/2066460715209138305 · Twitter Post
• https://t.me/avleonovcom/1631 · Telegram Post
• https://twitter.com/Dark_Puzzle/status/2024895958459482483 · Twitter Post
• https://twitter.com/_jle_k/status/2026097229203742808 · Twitter Post