EUVD-2026-43845
GHSA-c6qf-23gr-mjqw
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Local access with low-privilege account required; no scope change, integrity, or availability impact; only kernel memory disclosure confirmed by description and CVSS.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Integer underflow (wrap or wraparound) in Windows Kernel allows an authorized attacker to disclose information locally.
AnalysisAI
Integer underflow in the Windows Kernel enables a locally authenticated attacker to disclose sensitive kernel memory contents across a broad range of Windows 10, Windows 11, and Windows Server platforms. The CVSS vector (AV:L/AC:L/PR:L/UI:N) confirms that any low-privilege local user can trigger the flaw without special configuration or user interaction, yielding high confidentiality impact with no integrity or availability consequences. Microsoft has released a patch via the July 2026 Security Update Guide; no public exploit has been identified at time of analysis, and the vulnerability is not listed in the CISA KEV catalog.
Technical ContextAI
The affected component is the Windows Kernel, present across CPE-confirmed platforms ranging from Windows 10 version 1607 through Windows 11 version 26H1 and Windows Server 2016 through 2019, with tags also referencing Server 2022 and Server 2025. CWE-191 (Integer Underflow / Wrap-or-Wraparound) describes an arithmetic condition where a value decrements below the minimum representable integer for its data type, causing it to wrap to a large positive value. In kernel context, this can corrupt pointer arithmetic or buffer-length calculations, causing the kernel to expose memory at unintended offsets to a calling user-mode process - potentially leaking security tokens, kernel pointers that defeat KASLR, or cryptographic keying material. The CPE strings use the 'application' type (cpe:2.3:a:microsoft:...) rather than the OS type, suggesting the flaw resides in a specific kernel component or in-box driver rather than the monolithic kernel image, though in practice all are kernel-mode and equally privileged.
RemediationAI
Apply the vendor-released patch by deploying the July 2026 Microsoft Security Update via Windows Update, WSUS, or the Microsoft Update Catalog as documented at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50300. The patch is confirmed available per Microsoft's advisory, though the exact patched build version numbers were not independently specified in the available intelligence data. As a compensating control where immediate patching is not feasible, restrict interactive logon and Remote Desktop rights to only explicitly trusted, named accounts on sensitive systems - particularly those hosting privileged workloads or domain controllers - since exploitation requires a locally authenticated session. Additionally, enforce application control policies (e.g., Windows Defender Application Control or AppLocker) to prevent untrusted code execution, which would block an attacker from running exploit code even if they hold a local account. Note that these compensating controls reduce exposure but do not eliminate the underlying kernel flaw.
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Same weakness CWE-191 – Integer Underflow
View allSame technique Information Disclosure
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External POC / Exploit Code
Leaving vuln.today