EUVD-2026-56642
GHSA-352w-hccj-h98p
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local attack vector requiring a low-privileged session; out-of-bounds read in the kernel yields full C/I/A impact via privilege escalation with no scope change beyond the local system.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Out-of-bounds read in Windows Win32K allows an authorized attacker to elevate privileges locally.
AnalysisAI
Privilege escalation via an out-of-bounds read in the Windows Win32K kernel subsystem allows a local authenticated attacker to gain SYSTEM-level access across a broad range of Windows client and server versions. The CVSS 7.8 vector (AV:L/AC:L/PR:L/UI:N) reflects a low-complexity local attack with full C/I/A impact, meaning any low-privileged user or compromised process can exploit this to completely own the host. No public exploit code or CISA KEV listing has been identified at time of analysis; however, the 19 affected Windows SKUs spanning Server 2012 through Windows 11 26H1 make this a high-priority patch cycle item - particularly for Remote Desktop and terminal server deployments where untrusted local sessions are common.
Technical ContextAI
Win32K (win32k.sys) is the kernel-mode component of the Windows graphics and windowing subsystem, operating in ring 0 and handling window management, menus, and graphical device interface calls. CWE-125 (Out-of-bounds Read) occurs when the kernel reads beyond an allocated buffer boundary, which in this context can expose sensitive kernel memory addresses or control structures. In kernel space, an out-of-bounds read can be chained into a privilege escalation primitive by disclosing ASLR-defeating pointer values or corrupting adjacent memory. The affected surface spans all major Windows NT kernel versions from 6.2 (Server 2012) through 10.0.28000 (Windows 11 26H1), indicating the vulnerable code path exists across a very long-lived and widely deployed code lineage. The CVE tags include both 'Information Disclosure' and 'Buffer Overflow,' suggesting the out-of-bounds read may be leveraged both to leak memory and as a stepping stone to a write primitive.
RemediationAI
Apply vendor-released patches via Windows Update or WSUS as documented in the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62733. Exact fixed builds confirmed by EUVD data: Windows Server 2012 → 6.2.9200.26279; Windows Server 2012 R2 → 6.3.9600.23337; Windows Server 2016 and Windows 10 1607 → 10.0.14393.9418; Windows Server 2019 and Windows 10 1809 → 10.0.17763.9115; Windows Server 2022 → 10.0.20348.5499; Windows Server 2025 → 10.0.26100.33296; Windows 11 24H2 → 10.0.26100.9168; Windows 11 23H2 → 10.0.22631.7517; Windows 11 25H2 → 10.0.26200.9168; Windows 11 26H1 → 10.0.28000.2704; Windows 10 21H2 → 10.0.19044.7663; Windows 10 22H2 → 10.0.19045.7663. Where immediate patching is not feasible, reduce attack surface by restricting interactive and remote desktop logon rights to only trusted, managed accounts - this limits the pool of principals who can reach the Win32K attack surface but does not eliminate the vulnerability. On server infrastructure, enforce least-privilege local logon policies and audit privileged group membership.
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Same weakness CWE-125 – Out-of-bounds Read
View allSame technique Buffer Overflow
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External POC / Exploit Code
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