CVE-2025-21418: Microsoft Windows Ancillary Function Driver for WinSock Heap-Based Buffer Overflow Vulnerability
First published: Tue Feb 11 2025(Updated: )
Microsoft Windows Ancillary Function Driver for WinSock contains a heap-based buffer overflow vulnerability that allows for privilege escalation, enabling a local attacker to gain SYSTEM privileges.
Credit: secure@microsoft.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Microsoft Windows Server 2022 | ||
| Microsoft Windows Server 2008 Itanium | ||
| Microsoft Windows 10 | =1809 | |
| Microsoft Windows 10 | =22H2 | |
| Microsoft Windows 10 | =22H2 | |
| Microsoft Windows Server 2022 | ||
| Microsoft Windows 10 | =21H2 | |
| Microsoft Windows 11 | =22H2 | |
| Microsoft Windows Server 2025 | ||
| Microsoft Windows Server 2019 | ||
| Microsoft Windows Server 2022 23H2 | ||
| Microsoft Windows Server 2019 | ||
| Microsoft Windows Server 2012 x64 | ||
| Microsoft Windows 10 | =1809 | |
| Microsoft Windows Server 2008 R2 | ||
| Microsoft Windows 10 | =21H2 | |
| Microsoft Windows 11 | =24H2 | |
| Microsoft Windows Server 2016 | ||
| Microsoft Windows 10 | =1607 | |
| Microsoft Windows Server 2012 R2 | ||
| Microsoft Windows Server 2008 Itanium | ||
| Microsoft Windows 10 | =1607 | |
| Microsoft Windows 10 | ||
| Microsoft Windows Server 2025 | ||
| Microsoft Windows 11 | =24H2 | |
| Microsoft Windows 10 | =21H2 | |
| Microsoft Windows 11 | =22H2 | |
| Microsoft Windows Server 2012 x64 | ||
| Microsoft Windows Server 2012 R2 | ||
| Microsoft Windows 11 | =23H2 | |
| Microsoft Windows Server 2008 Itanium | ||
| Microsoft Windows 11 | =23H2 | |
| Microsoft Windows Server 2016 | ||
| Microsoft Windows 10 | ||
| Microsoft Windows Server 2008 R2 | ||
| Microsoft Windows Server 2008 Itanium | ||
| Microsoft Windows 10 | =22H2 | |
| Microsoft Windows | ||
| <10.0.10240.20915 | ||
| <10.0.10240.20915 | ||
| <10.0.17763.6893 | ||
| <10.0.17763.6893 | ||
| <10.0.19044.5487 | ||
| <10.0.19045.5487 | ||
| <10.0.22621.4890 | ||
| <10.0.22631.4890 | ||
| <10.0.26100.3194 | ||
| =sp2 | ||
| =r2-sp1 | ||
| =r2 | ||
| <10.0.17763.6893 | ||
| <10.0.20348.3207 | ||
| <10.0.25398.1425 | ||
| <10.0.26100.3194 | ||
| Microsoft Windows 10 Version 1607 x86 | <10.0.10240.20915 | |
| Microsoft Windows 10 Version 1607 x86 | <10.0.10240.20915 | |
| Microsoft Windows 10 1809 | <10.0.17763.6893 | |
| Microsoft Windows 10 1809 | <10.0.17763.6893 | |
| Microsoft Windows 10 21h2 | <10.0.19044.5487 | |
| Microsoft Windows 10 22h2 | <10.0.19045.5487 | |
| Microsoft Windows 11 22h2 | <10.0.22621.4890 | |
| Microsoft Windows 11 23h2 | <10.0.22631.4890 | |
| Microsoft Windows 11 Home Edition | <10.0.26100.3194 | |
| Microsoft Windows Server 2008 Itanium | =sp2 | |
| Microsoft Windows Server 2008 Itanium | =r2-sp1 | |
| Microsoft Windows Server 2012 x64 | ||
| Microsoft Windows Server 2012 x64 | =r2 | |
| Microsoft Windows Server 2016 | ||
| Microsoft Windows Server 2019 | <10.0.17763.6893 | |
| Microsoft Windows Server 2022 | <10.0.20348.3207 | |
| Microsoft Windows Server 2022 23H2 | <10.0.25398.1425 | |
| Microsoft Windows Server 2025 | <10.0.26100.3194 |
Remedy
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
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Reference Links
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21418 (Advisory)
- https://nvd.nist.gov/vuln/detail/CVE-2025-21418
- https://www.darkreading.com/application-security/microsofts-february-patch-lighter-lift-januarys
- https://www.theregister.com/2025/02/12/patch_tuesday_february_2025/
- https://www.zdnet.com/article/dont-ignore-microsofts-february-patch-tuesday-its-a-big-one-for-all-windows-11-users/
Peer vulnerabilities
(Found alongside the following vulnerabilities)
Frequently Asked Questions
What is the severity of CVE-2025-21418?
CVE-2025-21418 has a high severity rating due to its heap-based buffer overflow vulnerability, which allows for privilege escalation.
How do I fix CVE-2025-21418?
To fix CVE-2025-21418, apply the latest security patch provided by Microsoft for the affected Windows versions.
Which versions of Windows are affected by CVE-2025-21418?
CVE-2025-21418 affects several versions of Windows, including Windows 11, various Windows Server editions, and specific builds of Windows 10.
What type of vulnerability is CVE-2025-21418?
CVE-2025-21418 is categorized as an elevation of privilege vulnerability due to a heap-based buffer overflow in the Ancillary Function Driver for WinSock.
Who is impacted by CVE-2025-21418?
Local attackers on vulnerable systems can exploit CVE-2025-21418 to gain SYSTEM privileges, making it critical for system administrators to address.
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