EUVD-2026-56390
GHSA-fc2p-3vxp-vhj9
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local attack requiring only a low-privilege account; no user interaction; full kernel-level C/I/A impact consistent with SYSTEM escalation via ntfs.sys heap corruption.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Heap-based buffer overflow in Windows NTFS allows an authorized attacker to elevate privileges locally.
AnalysisAI
Privilege escalation via heap-based buffer overflow in the Windows NTFS driver enables a local authenticated attacker with standard user rights to gain SYSTEM-level control on affected Windows endpoints and servers. The vulnerability spans a wide swath of the Windows ecosystem, from Windows Server 2012 through Windows Server 2025 and Windows 11 26H1, making the aggregate exposure significant. No public exploit code or CISA KEV listing is confirmed at time of analysis, but the low attack complexity (AC:L) and absence of user interaction (UI:N) mean that a working exploit would be highly reliable once developed.
Technical ContextAI
CWE-122 (Heap-based Buffer Overflow) identifies the root cause: the NTFS filesystem driver (ntfs.sys) performs an out-of-bounds write to heap memory when processing a crafted filesystem structure or IOCTL input. Because NTFS operates in kernel mode, a successful heap overflow at this layer can corrupt kernel data structures or function pointers, enabling control-flow hijacking and execution of attacker-controlled code with kernel privileges. The CVSS vector AV:L/PR:L confirms that the attacker must have local, low-privilege access - consistent with a standard domain or local user triggering a malformed NTFS operation. Affected products span Windows build series 6.2.x (Server 2012), 6.3.x (Server 2012 R2), 10.0.14393.x (Server 2016, Windows 10 1607), 10.0.17763.x (Server 2019, Windows 10 1809), 10.0.19044/19045.x (Windows 10 21H2/22H2), 10.0.20348.x (Server 2022), and 10.0.22631/26100/26200/28000.x (Windows 11 and Server 2025 variants).
RemediationAI
The primary remediation is to apply Microsoft's security updates via Windows Update or WSUS, upgrading each affected build to or beyond the patched build numbers confirmed in EUVD data: Windows Server 2012 to 6.2.9200.26279 or later, Windows Server 2012 R2 to 6.3.9600.23337 or later, Windows 10/Server 2016 (1607) to 10.0.14393.9418 or later, Windows 10/Server 2019 (1809) to 10.0.17763.9115 or later, Windows 10 21H2 to 10.0.19044.7663 or later, Windows 10 22H2 to 10.0.19045.7663 or later, Windows Server 2022 to 10.0.20348.5499 or later, Windows 11 23H2 to 10.0.22631.7517 or later, Windows 11 24H2 to 10.0.26100.9168 or later, Windows 11 25H2 to 10.0.26200.9168 or later, Windows 11 26H1 to 10.0.28000.2704 or later, and Windows Server 2025 to 10.0.26100.33296 or later. Full advisory is at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62797. For systems where immediate patching is not feasible - particularly Windows Server 2012/2012 R2, which are end-of-life - compensating controls include enforcing least-privilege user accounts to limit the pool of users who can trigger NTFS operations, enabling Windows Defender Credential Guard to protect kernel memory integrity, and deploying Microsoft Defender for Endpoint with Attack Surface Reduction rules to detect anomalous privilege escalation attempts. Note that ASR rules reduce exploit reliability but do not eliminate the vulnerability.
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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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