EUVD-2026-44296
GHSA-m7m8-cc54-66jh
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local kernel EoP by an authenticated low-privileged user (AV:L, PR:L, UI:N); use-after-free yields full SYSTEM control giving C:H/I:H/A:H with unchanged scope.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
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) allows an authenticated low-privileged user to elevate to SYSTEM by triggering a use-after-free memory corruption condition. The flaw affects a broad range of Windows client and server releases (Windows 10 1809 through Windows 11 26H1, and Windows Server 2019 through 2025) and was reported by Microsoft. There is no public exploit identified at time of analysis and the CVE is not listed in CISA KEV.
Technical ContextAI
The Cloud Files Mini Filter Driver (cldflt.sys) is a kernel-mode file system minifilter that underpins the Windows Cloud Files API / 'Files On-Demand' placeholder functionality used by OneDrive and other cloud sync providers. As a filter-manager component, it runs in kernel context and mediates I/O for reparse-point placeholder files. The root cause is CWE-416 (Use After Free): the driver references a kernel object after it has been freed, allowing an attacker who controls the timing/lifetime of that object to reuse the freed allocation with attacker-influenced data, corrupting kernel memory and hijacking execution flow in ring 0.
RemediationAI
Patch available per vendor advisory: apply the Microsoft security update for CVE-2026-58536 for your specific Windows SKU as documented at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58536 (delivered through the standard cumulative/Patch Tuesday channel). The input does not provide an exact fixed build number, so identify the correct KB per OS version from the MSRC guide. Because this is a local elevation-of-privilege flaw with no vendor-listed configuration workaround, the primary control is prompt patch deployment prioritized on multi-user and interactively-accessed hosts (RDP/terminal servers, jump boxes, shared workstations). As compensating controls until patching, restrict interactive and local logon rights to reduce the population of accounts that could trigger the flaw, and enforce application allow-listing (e.g., WDAC/AppLocker) to limit an attacker's ability to run the exploit binary - noting the trade-off that these do not remove the vulnerability and add administrative overhead. Disabling OneDrive/Files On-Demand may reduce exercise of the Cloud Files driver but is not confirmed by the vendor as a mitigation and could break cloud sync workflows, so treat it as unverified.
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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