How severe is CVE-2025-21418?

CVE-2025-21418 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2025-21418 being actively exploited?

Yes. CVE-2025-21418 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2025-02-11, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2025-21418?

CVE-2025-21418 primarily affects Microsoft Windows 10 1607. In total, 18 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-21418?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2025-21418 have an EU (EUVD) identifier?

Yes. CVE-2025-21418 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-2476. It is also flagged as exploited in the EUVD (since 2025-02-11).

When was CVE-2025-21418 published?

CVE-2025-21418 was published on 2025-02-11 and last updated on 2026-06-17.

CVE-2025-21418

CVE-2025-21418 is a high-severity vulnerability in Microsoft Windows 10 1607 with a CVSS 3.x base score of 7.8. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2025-02-11). The underlying weakness is classified as CWE-122.

Key facts

Severity: High (CVSS 3.x base score 7.8)
EPSS exploit prediction: 1% (70th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2025-02-11)
EU (EUVD) id: EUVD-2025-2476
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2025-02-11)
Weakness: CWE-122
Affected product: Microsoft Windows 10 1607
Published: 2025-02-11
Last modified: 2026-06-17

Description

Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

Frequently asked questions

What is CVE-2025-21418?: Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
How severe is CVE-2025-21418?: CVE-2025-21418 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2025-21418 being actively exploited?: Yes. CVE-2025-21418 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2025-02-11, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2025-21418?: CVE-2025-21418 primarily affects Microsoft Windows 10 1607. In total, 18 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-21418?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2025-21418 have an EU (EUVD) identifier?: Yes. CVE-2025-21418 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-2476. It is also flagged as exploited in the EUVD (since 2025-02-11).
When was CVE-2025-21418 published?: CVE-2025-21418 was published on 2025-02-11 and last updated on 2026-06-17.

References

Affected products (18)

cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*
cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_22h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*

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