Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Local delivery of a crafted volume (AV:L) that the victim must mount (UI:R) with no auth (PR:N); kernel-context code execution gives full C/I/A impact.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Heap-based buffer overflow in Windows Resilient File System (ReFS) allows an unauthorized attacker to execute code locally.
AnalysisAI
Local code execution in Microsoft Windows' Resilient File System (ReFS) driver lets an unauthorized attacker run arbitrary code by inducing a victim to mount or open a maliciously crafted ReFS volume (CVE-2026-50362). The flaw affects the ReFS component shipped across Windows 10, Windows 11 (through 26H1), and Windows Server 2016-2025, carries CVSS 7.8, and requires user interaction (UI:R) with no prior authentication (PR:N). Microsoft has released a patch; there is no public exploit identified at time of analysis and it is not listed in CISA KEV.
Technical ContextAI
The vulnerability is a heap-based buffer overflow (CWE-122) in the Resilient File System (ReFS), Microsoft's copy-on-write filesystem used for Storage Spaces, Windows Server data volumes, and Dev Drive. When the ReFS kernel-mode driver parses on-disk metadata structures from a volume, insufficient bounds validation allows attacker-controlled data to write past an allocated heap buffer, corrupting adjacent kernel heap memory. Because the parsing runs in kernel context, controlled corruption of ReFS metadata can be leveraged to hijack execution flow. The affected CPEs enumerate the ReFS-bearing OS builds: Windows 10 (1607, 1809, 21H2, 22H2), Windows 11 (24H2, 25H2, 26H1), and Windows Server 2016, 2019, 2022, and 2025 including Server Core installations.
RemediationAI
Patch available per vendor advisory - apply the Microsoft security update for CVE-2026-50362 for the specific Windows or Windows Server build in use, which is delivered through the monthly cumulative update; consult https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50362 for the exact fixed build number matching each affected version. Where immediate patching is not possible, reduce exposure by restricting the ability to mount untrusted ReFS volumes: block or restrict auto-mounting of removable media and disk images via Group Policy device installation restrictions, disallow mounting of user-supplied VHD/VHDX and physical volumes on sensitive hosts, and train users not to open or mount storage from untrusted sources. On systems that do not use ReFS these controls have minimal operational impact, but on Storage Spaces or Dev Drive hosts restricting volume mounting may interrupt legitimate storage workflows, so scope the controls to endpoints that handle external media.
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Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Heap Overflow
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External POC / Exploit Code
Leaving vuln.today
EUVD-2026-44071
GHSA-qmfc-cvq2-hfwh