EUVD-2026-43808
GHSA-hv8x-xmjg-mmxp
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local vector with low privilege required (attacker needs an existing foothold to drive the ReFS heap path), no user interaction, and driver-context code execution yields full C/I/A impact with unchanged scope.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
2DescriptionCVE.org
Heap-based buffer overflow in Windows Resilient File System (ReFS) allows an authorized attacker to execute code locally.
AnalysisAI
Local privilege escalation via arbitrary code execution in Microsoft Windows Resilient File System (ReFS) affects a broad range of Windows 10, Windows 11, and Windows Server (2016-2025) builds. An authorized (low-privileged) attacker who can trigger the vulnerable heap allocation path can corrupt heap memory (CWE-122) to run code in the security context of the ReFS driver, yielding full confidentiality, integrity, and availability impact. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the target host to have an ReFS-formatted volume present and reachable by the attacker, plus an existing low-privileged local account or code-execution foothold on that host (CVSS PR:L) - this is not remotely exploitable (AV:L) and requires no user interaction (UI:N). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 base score of 7.8 (High) reflects easy local exploitation: AV:L (local vector), AC:L (low complexity), PR:L (some existing privilege required), UI:N (no user interaction), and full H/H/H impact. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker who has already gained low-privileged access to a Windows or Windows Server host with an ReFS volume (for example, a standard user account or a compromised low-privilege service) crafts input or file-system operations that drive the vulnerable ReFS code path into a heap overflow. By controlling the overflowing data, they corrupt adjacent heap structures to hijack execution and elevate to SYSTEM-level code execution. … |
| Remediation | Apply the Microsoft security update for CVE-2026-49793 (Patch available per vendor advisory) via the standard Windows Update / WSUS / Microsoft Update Catalog channel; consult the MSRC guidance at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-49793 for the exact KB and fixed build numbers for each affected OS version, as those were not enumerated in the input data. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all Windows 10, 11, and Server 2016-2025 systems utilizing ReFS and determine patch applicability per Microsoft advisory. …
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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
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