Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
CVE-2025-21418 is an elevation-of-privilege vulnerability in the Windows Ancillary Function Driver for WinSock (AFD.sys). The provided content consistently identifies the affected component as AFD.sys and states that successful exploitation allows execution of a specially crafted local program to elevate privileges to SYSTEM. Multiple sources in the content note that the vulnerability was under active exploitation in the wild at the time of Microsoft’s February 2025 Patch Tuesday release. Although one mention context characterizes it as similar to prior AFD.sys use-after-free issues, the provided material does not supply authoritative technical details such as the exact vulnerable function, code path, or a confirmed CWE classification for this specific CVE.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
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Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
8 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A Windows Ancillary Function Driver (AFD) vulnerability (kernel/user boundary) discussed in the context of recent AFD zero-days; treated as a likely elevation-of-privilege issue affecting kernel parsing of user-mode input.
An elevation of privilege vulnerability in the Windows Ancillary Function Driver for WinSock.
A Windows Ancillary Function Driver for WinSock elevation of privilege vulnerability that Microsoft reports is under active exploitation in the wild.
Another use-after-free vulnerability in the Windows AFD.sys driver that was reportedly exploited by ransomware actors.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.