EUVD-2026-43785
GHSA-wr2w-mf8c-jf9v
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Local interactive access with a standard user account required; high confidentiality from memory disclosure but no integrity or availability impact applies.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Use of uninitialized resource in Windows File Explorer allows an authorized attacker to disclose information locally.
AnalysisAI
Windows File Explorer across a broad range of Windows 10, Windows 11, and Windows Server releases contains a use-of-uninitialized-resource flaw (CWE-908) that allows a low-privileged local attacker to read stale memory contents and disclose potentially sensitive information. The vulnerability is locally constrained (AV:L, PR:L) with no integrity or availability impact, and SSVC signals no known exploitation and no automatable attack path. EPSS at 0.31% (22nd percentile) and the absence of a CISA KEV entry collectively indicate low near-term exploitation likelihood despite the wide deployment footprint of the affected OS.
Technical ContextAI
CWE-908 (Use of Uninitialized Resource) describes a condition where allocated memory or a system resource is consumed before it has been properly zeroed or initialized, exposing residual data from prior allocations to the caller. In Windows File Explorer, this flaw manifests in the shell's processing pipeline - likely in folder enumeration, file metadata parsing, or thumbnail/icon rendering - where a buffer is allocated but its contents are read before initialization, potentially surfacing fragments of heap memory that may include sensitive strings, path data, or cached user context. The affected code runs in the context of the Windows shell (explorer.exe). CPE data confirms impact across the cpe:2.3:a:microsoft:windows_10_version_1607 through cpe:2.3:a:microsoft:windows_server_2019 product families, spanning a decade of Windows releases. The CVSS AV:L constraint confirms this is a local-only attack surface with no network-facing exposure.
RemediationAI
The primary remediation is applying Microsoft's cumulative update to reach the fixed build thresholds: Windows 10 1607 and Server 2016 to build 10.0.14393.9339 or later; Windows 10 1809 and Server 2019 to 10.0.17763.9020 or later; Windows 10 21H2 to 10.0.19044.7548 or later; Windows 10 22H2 to 10.0.19045.7548 or later; Windows 11 24H2 to 10.0.26100.8875 or later; Windows 11 25H2 to 10.0.26200.8875 or later; Windows 11 26H1 to 10.0.28000.2269 or later; Windows Server 2022 to 10.0.20348.5386 or later; and Windows Server 2025 to 10.0.26100.33158 or later. Updates are available through Windows Update and the Microsoft Update Catalog; the vendor patch advisory is at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40422. If patching cannot be immediately applied on shared multi-user systems such as terminal servers or VDI hosts, restricting interactive logon rights to only explicitly trusted users via Group Policy (User Rights Assignment: 'Allow log on locally') reduces the pool of principals who could trigger exploitation - note this does not eliminate the flaw, only limits who can reach it. No other vendor-documented workaround is available at time of analysis.
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Same weakness CWE-908 – Use of Uninitialized Resource
View allSame technique Information Disclosure
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External POC / Exploit Code
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