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CVE-2025-21418

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

7.8 HIGHActively exploited (CISA KEV)EPSS 1.57%
  1. Published11 Feb 2025
  2. Added to CISA KEV11 Feb 2025
  3. Remediation due4 Mar 2025
Actively exploited (CISA KEV)

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.

Added to KEV: 11 Feb 2025Federal remediation due: 4 Mar 2025

Description

Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

CVSS 3.1 breakdown

Attack vectorLocal
Attack complexityLow
Privileges requiredLow
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

Microsoft Windows 10 1607< 10.0.10240.20915
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 24h2< 10.0.26100.3107
Microsoft Windows Server 2008r2
Microsoft Windows Server 2012r2
Microsoft Windows Server 2016< 10.0.14393.7785
Microsoft Windows Server 2019< 10.0.17763.6893
Microsoft Windows Server 2022< 10.0.20348.3148
Microsoft Windows Server 2022 23h2< 10.0.25398.1425
Microsoft Windows Server 2025< 10.0.26100.3107

Remediation

Fixed in
Microsoft Windows 10 1607≥ 10.0.10240.20915
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 24h2≥ 10.0.26100.3107
Microsoft Windows Server 2016≥ 10.0.14393.7785
Microsoft Windows Server 2019≥ 10.0.17763.6893
Microsoft Windows Server 2022≥ 10.0.20348.3148

References

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Frequently asked

Is CVE-2025-21418 being actively exploited?

Yes. CVE-2025-21418 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 11 Feb 2025.

How severe is CVE-2025-21418?

CVE-2025-21418 has a CVSS 3.1 base score of 7.8, rated high. EPSS estimates a 1.57% probability of exploitation.

Which products are affected by CVE-2025-21418?

Affected products include Microsoft Windows 10 1607, Microsoft Windows 10 1809, Microsoft Windows 10 21h2, Microsoft Windows 10 22h2, Microsoft Windows 11 22h2, and 9 more.

How do I fix CVE-2025-21418?

Upgrade affected software to a fixed version, for example Microsoft Windows 10 1607 10.0.10240.20915, Microsoft Windows 10 1809 10.0.17763.6893, Microsoft Windows 10 21h2 10.0.19044.5487 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2025-21418 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.