Windows
CVE-2026-21248
HIGH
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessAttacker with local account logs in
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DeliveryOpens Hyper-V management interface
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ExploitSends crafted input to VM configuration
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ExecutionTriggers heap buffer overflow
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ImpactExecutes arbitrary code with Hyper-V privileges
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Heap buffer bounds checking
MITRE ATT&CK
1 technique across 1 tactic: Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Requires local system access with standard user privileges (PR:L). Attacker must interact with Hyper-V management console or API (UI:R). Hyper-V role must be installed and enabled on Windows Server or Windows Pro/Enterprise with virtualization enabled. |
| Impact | CVSS 7.3 (HIGH). Attack vector: Local. Complexity: Low. Privileges required: Low. User interaction: Required. Exploitable via local access. |
| Exploit ScenarioDerived | An attacker could exploit this vulnerability to compromise the affected system. |
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Alert meAnalysisAIv1 – Mar 12, 2026
Heap overflow in Windows Hyper-V enables authenticated local users to achieve arbitrary code execution with high privileges on affected Windows and Windows Server systems. An attacker with local access and user-level permissions can trigger memory corruption through user interaction to compromise system integrity and confidentiality. This vulnerability affects Windows 10 1809, Windows Server 2025, and related Hyper-V implementations with no patch currently available.
Earlier versions of this analysis (1)
Heap-based buffer overflow in Windows Hyper-V allows an authorized attacker to execute code locally. [CVSS 7.3 HIGH]
RemediationAI
Monitor vendor advisories for a patch. Enable ASLR, DEP/NX, and stack canaries where possible.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 13 packages in microsoft
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Classified as CWE-122 (Heap-based Buffer Overflow). Affects Windows 10 1607. Heap-based buffer overflow in Windows Hyper-V allows an authorized attacker to execute code locally.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionCVE.org
Heap-based buffer overflow in Windows Hyper-V allows an authorized attacker to execute code locally.
Executive ViewAI
A high-severity heap buffer overflow in Windows Hyper-V allows authenticated attackers with local access to execute arbitrary code, potentially compromising virtualized environments and hosted workloads. Organizations running Hyper-V infrastructure should treat this as a critical threat requiring immediate containment measures, as no patch is currently available.
Restrict Hyper-V administrative access using group policies and role-based access control (RBAC) to authorized personnel only; disable unnecessary remote management protocols (RDP, WinRM) on Hyper-V hosts; implement network segmentation isolating Hyper-V infrastructure from general enterprise networks; enforce multi-factor authentication for all administrative access; deploy host-based intrusion detection on Hyper-V servers; disable guest integration services if not required; monitor process execution and memory access on Hyper-V hosts for anomalous activity.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Exploit-DB
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.
A heap overflow occurs when a program writes data beyond the bounds of a buffer allocated in the heap memory region.
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GitHub PoC