CVE-2025-21418: Microsoft Windows Ancillary Function Driver for WinSock Heap-Based Buffer Overflow Vulnerability

CVE-2025-21418 · Severity: critical · CVSS 7.8 · Exploited in the wild · Published 2025-02-11

The Microsoft Windows Ancillary Function Driver (AFD) for WinSock contains a heap-based buffer overflow vulnerability. A local attacker can exploit this flaw to escalate privileges and gain SYSTEM-level access on affected Windows operating systems.

Technologies: Microsoft Windows. Vendors: Microsoft.

Quick answers

Is CVE-2025-21418 exploited in the wild?
Yes. CVE-2025-21418 is known to be exploited in the wild, first recorded on 11 February 2025. Treat it as urgent.
How severe is CVE-2025-21418?
Critical severity, with a CVSS score of 7.8, published 11 February 2025.
Which products and versions are affected?
Microsoft Windows 10 1607, 1809, 21H2, 22H2; Microsoft Windows 11 22H2, 23H2, 24H2; Microsoft Windows Server 2008, 2012, 2016, 2019, 2022, 2025.
Is there a fix for CVE-2025-21418?
A patch was published on 2025-02-11. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2025-21418 attacked?
It is attacked with local access, in an operating system.
Am I affected by CVE-2025-21418?
Check whether you run Microsoft Windows. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Affected products

  • Microsoft Windows 10 1607, 1809, 21H2, 22H2
  • Microsoft Windows 11 22H2, 23H2, 24H2
  • Microsoft Windows Server 2008, 2012, 2016, 2019, 2022, 2025

Timeline

  • 2025-02-11: disclosed
  • 2025-02-11: patched
  • 2025-02-11: kev added: Added to CISA KEV catalog.
  • 2025-02-11: exploited: Reported as exploited in the wild.

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