How severe is CVE-2025-21418?

CVE-2025-21418 has a CVSS 3.1 base score of 7.8 (HIGH). EPSS estimates a 1.6% probability of exploitation in the next 30 days. It is listed in the CISA Known Exploited Vulnerabilities catalog.

CVE-2025-21418: Windows Ancillary Function Driver for WinSock

CISA Known Exploited Vulnerabilities

Microsoft Windows Ancillary Function Driver for WinSock Heap-Based Buffer Overflow Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.

Added to KEV

2025-02-11

Remediation due

2025-03-04

Required action
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

CISA notes
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21418 ; https://nvd.nist.gov/vuln/detail/CVE-2025-21418

Description

Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

Severity

CVSS 3.1 · CNA7.8 HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

SSVC · CISA-ADP

Exploitationactive

Automatableno

Technical impacttotal

Affected Products

Vendor	Product	Affected versions
Microsoft	Windows 10 Version 1507	10.0.10240.0 to <10.0.10240.20915
Microsoft	Windows 10 Version 1607	10.0.14393.0 to <10.0.14393.7785
Microsoft	Windows 10 Version 1809	10.0.17763.0 to <10.0.17763.6893
Microsoft	Windows 10 Version 21H2	10.0.19044.0 to <10.0.19044.5487
Microsoft	Windows 10 Version 22H2	10.0.19045.0 to <10.0.19045.5487
Microsoft	Windows 11 version 22H2	10.0.22621.0 to <10.0.22621.4890
Microsoft	Windows 11 version 22H3	10.0.22631.0 to <10.0.22631.4890
Microsoft	Windows 11 Version 23H2	10.0.22631.0 to <10.0.22631.4890
Microsoft	Windows 11 Version 24H2	10.0.26100.0 to <10.0.26100.3194
Microsoft	Windows Server 2008 R2 Service Pack 1	6.1.7601.0 to <6.1.7601.27566
Microsoft	Windows Server 2008 R2 Service Pack 1 (Server Core installation)	6.1.7601.0 to <6.1.7601.27566
Microsoft	Windows Server 2008 Service Pack 2	6.0.6003.0 to <6.0.6003.23117
Microsoft	Windows Server 2008 Service Pack 2 (Server Core installation)	6.0.6003.0 to <6.0.6003.23117
Microsoft	Windows Server 2012	6.2.9200.0 to <6.2.9200.25317
Microsoft	Windows Server 2012 (Server Core installation)	6.2.9200.0 to <6.2.9200.25317
Microsoft	Windows Server 2012 R2	6.3.9600.0 to <6.3.9600.22417
Microsoft	Windows Server 2012 R2 (Server Core installation)	6.3.9600.0 to <6.3.9600.22417
Microsoft	Windows Server 2016	10.0.14393.0 to <10.0.14393.7785
Microsoft	Windows Server 2016 (Server Core installation)	10.0.14393.0 to <10.0.14393.7785
Microsoft	Windows Server 2019	10.0.17763.0 to <10.0.17763.6893
Microsoft	Windows Server 2019 (Server Core installation)	10.0.17763.0 to <10.0.17763.6893
Microsoft	Windows Server 2022	10.0.20348.0 to <10.0.20348.3207
Microsoft	Windows Server 2022, 23H2 Edition (Server Core installation)	10.0.25398.0 to <10.0.25398.1425
Microsoft	Windows Server 2025	10.0.26100.0 to <10.0.26100.3194
Microsoft	Windows Server 2025 (Server Core installation)	10.0.26100.0 to <10.0.26100.3194

References

1 Links

Vendor advisories

Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

Record Details

Published

2025-02-11

Last updated

2026-02-26

Assigner (CNA)

microsoft

Credited to

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Related Tool Categories

Tool categories that test for or protect against this vulnerability class.

CWE-122 · Heap-based Buffer Overflow

Fuzzing Binary Exploitation

CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.