EUVD-2026-43999
GHSA-c68f-jj57-fpg7
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local kernel EoP requiring existing low-privileged code execution (AV:L/PR:L), no interaction, low complexity, yielding full SYSTEM control (C/I/A:H) with no scope change.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Heap-based buffer overflow in Windows Overlay Filter allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Overlay Filter (WOF) driver allows an authenticated low-privileged user to elevate to SYSTEM by triggering a heap-based buffer overflow (CWE-122). The flaw spans a broad range of client and server SKUs from Windows 10 1607 through Windows 11 26H1 and Windows Server 2012 R2 through Server 2025. Microsoft has shipped a patch; there is no public exploit identified at time of analysis and it is not listed in CISA KEV.
Technical ContextAI
The Windows Overlay Filter (WOF, wof.sys) is a kernel-mode filesystem filter driver that implements the transparent, per-file compression used by features such as Compact OS and DISM/CompactOS file compression, layering compressed backing data over NTFS. Because it runs in kernel context, a memory-safety defect here yields kernel-level impact. The root cause is CWE-122, a heap-based buffer overflow: attacker-influenced input is written past the bounds of a kernel pool allocation, corrupting adjacent heap structures. Per the affected CPE set, this spans Microsoft client Windows (10 1607/1809/21H2/22H2 and 11 24H2/25H2/26H1) and Windows Server (2012 R2 including Server Core, 2016, 2019, 2022, and 2025), indicating shared driver code across the modern Windows codebase rather than a single-SKU regression.
RemediationAI
Apply the Microsoft security update for CVE-2026-54987 (Patch available per vendor advisory) for your specific SKU as documented at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-54987; consult that page for the exact fixed KB and build number per affected Windows release, as no single fixed version applies across all SKUs. No official pre-patch workaround is provided by the vendor in the available data. Because exploitation requires local low-privileged code execution, interim compensating controls that raise the bar include restricting interactive and remote-desktop logon rights to trusted users, enforcing least privilege to limit which accounts can run code on affected hosts, and enabling attack-surface-reduction rules and EDR monitoring for kernel-driver exploitation attempts; note these reduce likelihood but do not remove the vulnerability, so patching remains the only durable fix.
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Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Heap Overflow
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External POC / Exploit Code
Leaving vuln.today