What is the CVSS score of CVE-2025-21418?

CVE-2025-21418 has a CVSS 3.1 base score of 7.8 (High). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 13.6%.

Which versions of Windows are affected by CVE-2025-21418?

CVE-2025-21418 presents notable security risk, a heap-based buffer overflow vulnerability rated CVSS 7.8.. A patch is available.

Is CVE-2025-21418 being actively exploited?

Yes, CVE-2025-21418 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, confirming active in-the-wild exploitation. Immediate patching is required.

How to fix or mitigate CVE-2025-21418?

Within 24 hours: Identify all affected systems and apply vendor patches immediately. If patching is delayed, consider network segmentation to limit exposure.

Windows CVE-2025-21418

HIGH

Heap-based Buffer Overflow (CWE-122)

2025-02-11 secure@microsoft.com

Windows Buffer Overflow Heap Overflow Microsoft Windows 10 1607 Windows 10 1809 Windows 10 21h2 Windows 10 22h2 Windows 11 22h2 Windows 11 23h2 Windows 11 24h2 Windows Server 2008 Windows Server 2012 Windows Server 2016 Windows Server 2019 Windows Server 2022 Windows Server 2022 23h2 Windows Server 2025

7.8

CVSS 3.1

CVSS VectorNVD

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 28, 2026 - 18:26 vuln.today

Patch released

Mar 28, 2026 - 18:26 nvd

Patch available

Added to CISA KEV

Oct 27, 2025 - 17:13 cisa

CISA KEV

CVE Published

Feb 11, 2025 - 18:15 nvd

HIGH 7.8

DescriptionNVD

Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

AnalysisAI

Windows Ancillary Function Driver for WinSock contains a heap-based buffer overflow enabling local privilege escalation to SYSTEM, exploited in the wild in February 2025.

Technical ContextAI

The CWE-122 heap overflow in afd.sys allows local code to corrupt kernel heap memory through crafted Winsock operations. AFD.sys vulnerabilities are highly valued because the driver is always loaded and accessible from user mode without special privileges.

RemediationAI

Apply February 2025 Patch Tuesday update. Monitor for kernel exploitation indicators. Deploy Windows Defender Exploit Guard kernel protections.

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CVE-2025-21418 vulnerability details – vuln.today

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Windows CVE-2025-21418

CVSS VectorNVD

Lifecycle Timeline

DescriptionNVD

AnalysisAI

Technical ContextAI

RemediationAI

More from same product – last 7 days

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External POC / Exploit Code