PT-2021-6347 · Microsoft · Windows Ancillary Function Driver For Winsock+1

Erik Egsgard · Published 2021-09-14 · Updated 2025-12-16 · CVE-2021-38638

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 The issue is related to insufficient access restrictions in the Windows Ancillary Function Driver for WinSock, which can be exploited to elevate privileges. This allows an attacker to affect the system. No information is available about the estimated number of potentially affected devices or real-world incidents where this issue was exploited.

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

LPE

Improper Privilege Management

Weakness Enumeration

CWE-264

CWE-269

Related Identifiers

BDU:2022-01363

CVE-2021-38638

Affected Products

Windows

Windows Ancillary Function Driver For Winsock

References · 11

• https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2021-38638 · Vendor Advisory
• https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-38638 · Vendor Advisory
• https://bdu.fstec.ru/vul/2022-01363 · Security Note
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-38638 · Vendor Advisory
• http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-38638 · Security Note
• https://osv.dev/vulnerability/CVE-2021-38638 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2021-38638 · Security Note
• https://t.me/cibsecurity/28890 · Telegram Post
• https://cybersecurity-help.cz/vdb/SB2021091417 · Note
• https://t.me/cibsecurity/28878 · Telegram Post
• https://t.me/cveNotify/145985 · Telegram Post