EUVD-2026-44274
GHSA-c6cq-5j33-j5wh
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local access with a low-privileged foothold required (AV:L/PR:L), no user interaction, and kernel-mode UAF yielding SYSTEM gives total C/I/A impact within an unchanged scope.
Primary rating from Vendor (microsoft).
CVSS VectorNVD
Lifecycle Timeline
5DescriptionNVD
Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Ancillary Function Driver for WinSock (afd.sys) lets an already-authenticated user execute code in kernel context and gain SYSTEM-level rights, affecting a broad Windows client and server range from Windows Server 2012 through Windows 11 25H2/26H1 and Server 2025. The flaw is a CWE-416 use-after-free that yields total technical impact (C:H/I:H/A:H). Microsoft has shipped a patch; there is no public exploit identified at time of analysis and CISA's SSVC framework lists exploitation as none, with a low EPSS of 0.25% (16th percentile).
Technical ContextAI
AFD.sys is the kernel-mode Ancillary Function Driver that backs the Winsock user-mode API, mediating socket calls between user processes and the TCP/IP stack; it is a long-standing, high-value target for local exploitation because it is reachable from any process that opens a socket. The root cause is CWE-416 (use-after-free): the driver continues to reference a kernel object after it has been freed, allowing an attacker who can reallocate that memory to corrupt kernel state. Because the driver runs in ring 0, successful reuse of the dangling pointer translates directly into kernel-mode code execution or arbitrary read/write, which is why the SSVC technical impact is rated total. The CPE set spans microsoft:windows_10 (1607/1809/21H2/22H2), windows_11 (24H2/25H2/26H1), and windows_server 2012 through 2025, indicating the vulnerable code path is present across essentially the whole modern Windows lineage.
RemediationAI
Vendor-released patch available per Microsoft advisory - apply the cumulative Windows security update that raises each system to at least its fixed build: Windows 10 1607/Server 2016 to 10.0.14393.9339, Windows 10 1809/Server 2019 to 10.0.17763.9020, Windows 10 21H2 to 10.0.19044.7548, Windows 10 22H2 to 10.0.19045.7548, Windows 11 24H2/25H2 to 10.0.26100.8875, Windows 11 26H1 to 10.0.28000.2525, Server 2012 to 6.2.9200.26226, Server 2012 R2 to 6.3.9600.23291, Server 2022 to 10.0.20348.5386, and Server 2025 to 10.0.26100.33158, per https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-57093. There is no documented supported workaround because afd.sys is a core networking component that cannot be safely disabled without breaking Winsock connectivity; where patching must be delayed, reduce exposure by limiting the ability of untrusted users to run code on affected hosts (restrict interactive/terminal-server logon, enforce least privilege, and apply application allowlisting), accepting that these controls only shrink the attacker population rather than remove the vulnerable code path.
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Same weakness CWE-416 – Use After Free
View allSame technique Denial Of Service
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External POC / Exploit Code
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