CVE-2025-21418 | Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

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Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

Published: 2025-02-11 Last update: 2025-10-27 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-21418 is rated Critical Active Threat (88.8/100): CVSS High severity, with high exploitation likelihood (EPSS 13.27%, 94th percentile). CISA KEV confirms active exploitation (added 2025-02-11) affecting Microsoft / Windows. a weakness (CWE-122) Unauthenticated remote administrative access may be possible. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2025-21418

Name: Microsoft Windows Ancillary Function Driver for WinSock Heap-Based Buffer Overflow Vulnerability · CISA KEV detail

Exploit added: 2025-02-11

Action due: 2025-03-04

Required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Exploit prediction scoring system (EPSS) score for CVE-2025-21418

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-08 13.58% 13.27% -0.31%
2 2026-03-26 13.27% 13.58% +0.31%
3 2026-03-24 — 13.27% —

Full EPSS history (29 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-21418

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.9 [email protected]

Weakness enumeration for CVE-2025-21418

Affected software / configurations for CVE-2025-21418

Vendor Product Version Raw CPE
microsoft windows_10_1607 < 10.0.10240.20915 cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x64:*
microsoft windows_10_1607 < 10.0.10240.20915 cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*
microsoft windows_10_1809 < 10.0.17763.6893 cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:*
microsoft windows_10_1809 < 10.0.17763.6893 cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*
microsoft windows_10_21h2 < 10.0.19044.5487 cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:*:*
microsoft windows_10_22h2 < 10.0.19045.5487 cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:*:*
microsoft windows_11_22h2 < 10.0.22621.4890 cpe:2.3:o:microsoft:windows_11_22h2:*:*:*:*:*:*:*:*
microsoft windows_11_23h2 < 10.0.22631.4890 cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:*:*
microsoft windows_11_24h2 < 10.0.26100.3107 cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:*:*
microsoft windows_server_2008 — cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:*:*
microsoft windows_server_2008 r2 cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:*
microsoft windows_server_2012 — cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*
microsoft windows_server_2012 r2 cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*
microsoft windows_server_2016 < 10.0.14393.7785 cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*
microsoft windows_server_2019 < 10.0.17763.6893 cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
microsoft windows_server_2022 < 10.0.20348.3148 cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
microsoft windows_server_2022_23h2 < 10.0.25398.1425 cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:*
microsoft windows_server_2025 < 10.0.26100.3107 cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*

References for CVE-2025-21418

cvelogic Threat Intelligence