EUVD-2026-29596
GHSA-74mx-4mr5-g3wp
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local low-privileged user triggers a low-complexity kernel UAF with no interaction, yielding SYSTEM-level full compromise, so AV:L/PR:L/AC:L with C:H/I:H/A:H.
Primary rating from NVD.
CVSS VectorNVD
Lifecycle Timeline
2DescriptionCVE.org
Use after free in Windows Cloud Files Mini Filter Driver allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Cloud Files Mini Filter Driver (cldflt.sys) lets an authenticated low-privileged user corrupt kernel memory via a use-after-free and gain SYSTEM-level control across a broad range of Windows 10, Windows 11, and Windows Server builds. Microsoft has released fixes, but SSVC reports no observed exploitation and EPSS is very low (0.04%), so this is a patch-on-schedule kernel EoP rather than an emergency; no public exploit identified at time of analysis. Because Cloud Files underpins OneDrive/cloud sync placeholders, the driver is present on effectively every modern Windows install.
Technical ContextAI
The affected component is the Cloud Files Mini Filter Driver (cldflt.sys), a Windows kernel-mode filesystem minifilter that implements the Cloud Filter API used by sync engines such as OneDrive to manage placeholder/on-demand files. CWE-416 (Use After Free) means the driver references a memory object after it has been freed, allowing an attacker who controls timing/reallocation to place attacker-influenced data where a dangling kernel pointer is later used, yielding kernel-mode read/write or code execution. The CPE set (windows_10_version_1809 through windows_11_version_26h1, plus Windows Server 2019/2022/2025 including Server Core) confirms the flaw spans the mainline OS kernel filter stack rather than an optional add-on.
RemediationAI
Apply the Microsoft security update for your specific build - Vendor-released patch: install the cumulative update that brings the OS to at least the fixed revision (e.g., Windows 11 24H2 to 10.0.26100.8457, 25H2 to 10.0.26200.8457, Windows 10 22H2 to 10.0.19045.7291, Windows Server 2025 to 10.0.26100.32860, Server 2022 to 10.0.20348.5139, Windows 10/Server 2019 1809 to 10.0.17763.8755), per the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-34337. There is no documented supported configuration change that removes the vulnerable cldflt.sys, so patching is the primary and recommended control; as interim compensating measures, limit the number of interactive/low-privileged local users on affected hosts and enforce least privilege, since exploitation requires an existing local account. Because the driver backs cloud file placeholders, disabling OneDrive/Cloud Files sync is not a reliable mitigation (the minifilter still loads) and would break on-demand file features, so it is not recommended in lieu of the update.
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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
Leaving vuln.today