EUVD-2026-44050
GHSA-7vm6-25cv-9xxx
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local privilege escalation requiring an existing low-privileged foothold (AV:L, PR:L), no user interaction, with kernel-level compromise yielding full C/I/A impact.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Buffer over-read in Windows Overlay Filter allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Overlay Filter (WOF) driver affects a broad range of Windows client and server releases, from Windows 10 1607 and Server 2012 R2 through Windows 11 26H1 and Server 2025. An authenticated local attacker with low privileges can trigger a buffer over-read (CWE-126) in the filter to elevate to higher privileges, gaining full confidentiality, integrity, and availability impact on the host. Microsoft has released a patch; there is no public exploit identified at time of analysis and the CVE is not listed in CISA KEV.
Technical ContextAI
The affected component is the Windows Overlay Filter (WOF), a kernel-mode file system filter driver (wof.sys) used by Windows to support compressed file storage and Windows Image (WIM) overlay/backing scenarios, including features such as CompactOS and Windows container image layers. The root cause is classified as CWE-126 (Buffer Over-read), meaning the driver reads past the end of an allocated buffer - typically due to trusting an attacker-influenced length or offset without proper bounds validation. Because WOF operates in kernel context, memory it mishandles can be leveraged to corrupt or disclose kernel-controlled state, which is why the CVSS impact metrics rate confidentiality, integrity, and availability all High. The CPE data confirms this is a Microsoft-only issue spanning Windows 10 (1607/1809/21H2/22H2), Windows 11 (24H2/25H2/26H1), and Windows Server (2012 R2 through 2025, including Server Core installations).
RemediationAI
Apply the Microsoft security update for CVE-2026-50435; a patch is available per the vendor advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50435 (Patch available per vendor advisory - consult the MSRC page for the exact KB and patched build for each affected Windows/Windows Server SKU). Because this component ships as part of the OS, standard Windows Update / WSUS / Intune patch deployment is the primary and recommended fix, and no supported registry-toggle workaround was published in the input. As a compensating control until patching, reduce the population of low-privileged local users who can execute code on affected hosts - tighten access to RDP/terminal servers and shared multi-user systems, and apply least-privilege and application allow-listing so untrusted low-privilege code cannot run to reach the WOF driver; note the trade-off that these controls limit exposure but do not remove the underlying flaw. Prioritize Server Core and RDS/session hosts where local low-privilege access is most likely.
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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