CVE-2025-21418CISA KEV

Microsoft Windows Ancillary Function Driver for WinSock Heap-Based Buffer Overflow Vulnerability

Severity unknownCVSS unknownCheck the vendor advisory for fixed versions

CISA lists this Microsoft vulnerability as known exploited. Its MSRC release detail is outside this installation's collected history.

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CISA catalog record

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.

Product: Windows
Added to KEV: 11 Feb 2025
Federal remediation due: 4 Mar 2025
Known ransomware use: Not reported

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Field-level log (2)

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23 Oct 2026 · 09:33:49 UTC Source coverage: cisa-kevIncomplete → Current
23 Oct 2026 · 08:31:50 UTC Source coverage: cisa-kevCurrent → Incomplete

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Exploitation and risk

Source status

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CVE-2025-21418

Listed in CISA KEV · added 11 Feb 2025 · Microsoft · Windows

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.

CISA source

No EPSS score is available here for this CVE.

Saved 23 Oct 2026 16:01:26 UTC · View this risk record (JSON)

cve-program · CVE-2025-21418

Published

Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

Source published: 11 Feb 2025 17:58:17 UTC
Source modified: 26 Feb 2026 19:09:03 UTC
Saved here: 23 Oct 2026 15:48:27 UTC
Source terms: CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · 7.8 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