EUVD-2026-43867
GHSA-wq5c-w7mq-vqjv
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Requires a local low-privileged session (AV:L/PR:L) with no user interaction and low complexity; a kernel UAF yielding SYSTEM gives total C/I/A impact.
Primary rating from Vendor (microsoft).
CVSS VectorNVD
Lifecycle Timeline
5DescriptionNVD
Use after free in Windows TCP/IP allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows TCP/IP stack lets a low-privileged authenticated user corrupt kernel memory via a use-after-free (CWE-416) and elevate to SYSTEM. It affects a broad range of Windows 10, Windows 11, and Windows Server builds through 2025, was reported by Microsoft, and carries CVSS 7.8; there is no public exploit identified at time of analysis and EPSS is low (0.20%, 10th percentile).
Technical ContextAI
The flaw resides in the Windows TCP/IP kernel component (tcpip.sys), the core network protocol driver that processes IP/TCP/UDP traffic and socket operations in ring 0. The root cause is a use-after-free (CWE-416): a kernel object is freed while a dangling reference remains, and subsequent access to that stale pointer allows an attacker to manipulate freed-and-reallocated memory. Because the vulnerable code executes with kernel privileges, controlled reuse of the freed allocation can be leveraged to overwrite kernel structures or hijack execution flow, yielding SYSTEM-level control. The CPE set confirms the affected surface is the OS itself across client and server SKUs rather than an add-on application.
RemediationAI
Vendor-released patch available: apply the Microsoft security update that brings each build to at least the fixed version - 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, Server 2022 to 10.0.20348.5386, Windows 11 24H2 to 10.0.26100.8875 and Server 2025 to 10.0.26100.33158, Windows 11 25H2 to 10.0.26200.8875, and Windows 11 26H1 to 10.0.28000.2269 - per https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50307. Because the flaw is in the in-box TCP/IP kernel driver there is no supported configuration toggle to disable it, so patching is the only true fix; there is no vendor-published workaround. As compensating controls until patching, restrict and monitor local/interactive logon rights so fewer low-privileged accounts can run code on hosts (trade-off: does not stop an attacker who already has a foothold), and enforce least privilege plus EDR monitoring for kernel-exploitation and privilege-escalation behavior on unpatched systems (trade-off: detective, not preventive).
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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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