EUVD-2026-43850
GHSA-vmqg-mgpj-hj4m
Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Requires an authenticated local user (PR:L, AV:L) and hard-to-win memory conditions (AC:H); successful kernel EoP yields full SYSTEM control, so C/I/A all High with unchanged scope.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Buffer over-read in Windows Redirected Drive Buffering allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Redirected Drive Buffering Subsystem (RDBSS) lets an authenticated low-privileged attacker read memory beyond an allocated buffer to elevate to higher privileges. The flaw affects a broad range of currently-supported Windows client and server releases (Windows 10 1607 through Windows 11 26H1, Windows Server 2012 through Server 2025) and carries a CVSS 7.0 (High) rating. Microsoft has released a patch; there is no public exploit identified at time of analysis and the issue is not listed in CISA KEV.
Technical ContextAI
The Redirected Drive Buffering Subsystem (RDBSS, typically rdbss.sys) is a Windows kernel-mode component that provides buffering and mini-redirector support for network file systems such as SMB/CIFS drive redirection. CWE-126 (Buffer Over-read) is the root cause class: the driver reads past the end of a heap or stack buffer, most likely because a length or offset field is trusted without adequate bounds validation. Because RDBSS runs in kernel context, disclosed or mishandled out-of-bounds data can be leveraged to corrupt kernel state or leak sensitive kernel memory, which is why Microsoft rates confidentiality, integrity, and availability all High despite the bug being an over-read. The CPE data confirms the affected surface is the Windows operating system itself across Windows 10/11 and Windows Server 2012-2025 branches rather than any single application.
RemediationAI
Apply the Microsoft security update for your specific Windows build as the primary and complete fix - Patch available per vendor advisory; consult https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50372 for the exact KB article and fixed build number for each affected OS version, as no single cross-version fix string is provided in the input. Because exploitation requires an authenticated local foothold, effective compensating controls until patching completes include restricting interactive and RDP logon rights to trusted administrators, reducing the number of low-privilege users on sensitive servers, and enforcing least privilege and application allowlisting to limit an attacker's ability to run the code needed to trigger the flaw; note these controls reduce but do not eliminate risk on multi-user or terminal-server hosts and do not stop a malicious insider who already holds valid low-privilege credentials. Disabling network drive redirection is not a documented mitigation and could break file-sharing functionality, so prioritize patching over service changes.
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Same weakness CWE-126 – Buffer Over-read
View allSame technique Buffer Overflow
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External POC / Exploit Code
Leaving vuln.today