EUVD-2026-56348
GHSA-cg93-vwrm-9mr8
Severity by source
AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Physical media insertion is the sole access requirement; no privileges or user interaction needed; full kernel compromise achieved on success with no scope change.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Heap-based buffer overflow in Windows Universal Disk Format File System Driver (UDFS) allows an unauthorized attacker to execute code with a physical attack.
AnalysisAI
Heap-based buffer overflow in the Windows Universal Disk Format File System Driver (UDFS) enables kernel-level code execution through physical insertion of maliciously crafted UDF media, affecting every supported Windows client and server release from Server 2012 through Windows 11 26H1. The physical attack vector (AV:P) is the dominant risk constraint - a vendor patch is available from Microsoft and the vulnerability is not listed in CISA KEV. No public exploit has been identified at time of analysis, though the breadth of affected builds and the kernel execution context make this high priority in environments where physical access is not strictly controlled.
Technical ContextAI
Universal Disk Format (UDF) is an ISO/IEC 13346 and ECMA-167 standard file system originally designed for optical media (DVD, Blu-ray) and also supported on removable USB storage. Windows implements UDF parsing via the kernel-mode driver UDFS.sys, which processes volume structures automatically when removable media is mounted. CWE-122 (Heap-based Buffer Overflow) indicates that a specially crafted UDF volume structure causes the driver to write beyond the bounds of a heap allocation, corrupting adjacent kernel memory. Because UDFS.sys executes in Ring 0, successful exploitation yields arbitrary code execution at kernel privilege. The EUVD-2026-56348 data confirms the vulnerable code spans Windows builds from 6.2.9200 (Server 2012) through 10.0.28000 (Windows 11 26H1), suggesting the root-cause code path has been present for over a decade across the Windows UDF implementation.
RemediationAI
Apply the Microsoft security update immediately via Windows Update or WSUS; exact patched build thresholds confirmed by EUVD data are: Windows Server 2012 >= 6.2.9200.26279, Windows Server 2012 R2 >= 6.3.9600.23337, Windows Server 2016 >= 10.0.14393.9418, Windows Server 2019 / Windows 10 1809 >= 10.0.17763.9115, Windows Server 2022 >= 10.0.20348.5499, Windows Server 2025 / Windows 11 24H2 >= 10.0.26100.33296 (server) and 10.0.26100.9168 (client), Windows 10 21H2 >= 10.0.19044.7663, Windows 10 22H2 >= 10.0.19045.7663, Windows 11 23H2 >= 10.0.22631.7517, Windows 11 25H2 >= 10.0.26200.9168, and Windows 11 26H1 >= 10.0.28000.2704. The full advisory is at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62699. Where patching cannot be applied immediately, disable AutoPlay and AutoRun for all removable media drives via Group Policy (Computer Configuration > Administrative Templates > Windows Components > AutoPlay Policies > Turn off AutoPlay, set to All Drives); this prevents automatic UDFS.sys invocation on media insertion but does not block exploitation if an attacker can manually trigger volume mounting. Physically blocking USB and optical drive ports (via port blockers or BIOS/UEFI settings) is the most effective compensating control for high-value unattended systems; note this disrupts legitimate removable media workflows.
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Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Buffer Overflow
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External POC / Exploit Code
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