EUVD-2026-99751
GHSA-4g3w-6878-7wfc
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessObtain low-privileged local access on Hyper-V host
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DeliveryTrigger use-after-free in Hyper-V component
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ExploitCorrupt freed kernel object memory
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ExecutionExecute code at hypervisor/SYSTEM level
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ImpactFull host compromise
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Memory lifecycle management
MITRE ATT&CK
2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Requires the Hyper-V role/feature to be enabled on the target Windows host and the attacker to already possess authenticated local access (PR:L) - this is not remotely reachable (AV:L). No user interaction is needed (UI:N) and attack complexity is low (AC:L), so once a low-privileged local foothold exists on a Hyper-V-enabled system, escalation is straightforward. Limiting factors: hosts without the Hyper-V role enabled are not affected, remote-only attackers cannot trigger it without first gaining local code execution, and patched builds (e.g. Windows 11 24H2 >=10.0.26100.9711, Windows Server 2025 >=10.0.26100.33650) are not vulnerable. |
| Impact | This is a genuine but not emergency-grade priority. The CVSS 3.1 base score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) describes a local, low-complexity privilege escalation requiring attackers to already hold low-level authenticated access on the host, with total confidentiality, integrity and availability impact once triggered. CISA's SSVC framework reinforces a measured posture: Exploitation is rated 'none' (no observed or public exploitation), Automatable is 'no' (consistent with AV:L requiring pre-existing local foothold, so no mass/wormable scaling), while Technical Impact is 'total' (aligning with the C:H/I:H/A:H and the CWE-416 use-after-free that can yield kernel/hypervisor-level control). No EPSS score is provided in the input, so exploitation probability cannot be quantified here. It is not in CISA KEV and no public exploit is identified, so this is not a high-CVSS/low-real-risk false alarm, but neither is it under active exploitation - it is a serious local EoP in a sensitive hypervisor component that should be patched on normal-to-expedited cadence, prioritized on multi-tenant or shared Hyper-V hosts where a low-privileged tenant escaping to the host is the core threat. |
| Exploit ScenarioDerived | A low-privileged but authenticated attacker already running code on a Windows host with Hyper-V enabled (for example, a guest/tenant context or a limited local user) triggers the use-after-free in the Hyper-V component to corrupt kernel/hypervisor memory and elevate to SYSTEM or host-level control. No user interaction and no special privileges beyond an existing foothold are required, though local access must first be obtained. No public exploit code has been identified at time of analysis, so weaponization would require independent development. |
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Alert meAnalysisAIv1 – Oct 13, 2026
Local privilege escalation in Windows Hyper-V allows an authenticated, low-privileged user on a Hyper-V-enabled Windows host to trigger a use-after-free and execute code at a higher integrity level, ultimately reaching SYSTEM-level privileges on the host. The flaw carries a CVSS 3.1 base score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H), affecting Windows 11 24H2, 25H2, 26H1 and 26H2 as well as Windows Server 2025 builds prior to their fixed levels, and is only reachable once the attacker already holds local access on a system where the Hyper-V role is enabled. No public exploit identified at time of analysis, and CISA's SSVC decision framework records exploitation as none with the attack assessed as not automatable.
RemediationAI
Vendor-released patch: apply the current Microsoft security update so that affected systems reach the fixed builds Windows 11 24H2 >= 10.0.26100.9711, Windows 11 25H2 >= 10.0.26200.9711, Windows 11 26H1 >= 10.0.28000.3231, Windows 11 26H2 >= 10.0.26300.9711, and Windows Server 2025 (including Server Core) >= 10.0.26100.33650; patch availability and the exact per-SKU package mapping are documented in the MSRC update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-96223, and this should be treated as a standard local privilege-escalation fix rather than an emergency out-of-band action given the SSVC exploitation rating of none and the absence of public exploit code. Because the vulnerability is local and requires an existing authenticated foothold, the highest-value compensating controls are those that shrink that foothold and reduce virtualization exposure on unpatched hosts: if Hyper-V and its dependent virtualization features are not required on a given system, disabling the role removes the attack surface entirely (trade-off: loss of VMs, Windows Sandbox, WSL2, VBS/Credential Guard and other Hyper-V-backed security features), and where Hyper-V must stay enabled, restrict interactive logon and RDP access to trusted administrators, remove unnecessary accounts from the Hyper-V Administrators and local Administrators groups, and block low-privileged processes and non-administrative services from running on hypervisor hosts (trade-off: tighter operational restrictions on shared management endpoints). Enforcing least privilege, credential hygiene and privileged access workstations on virtualization hosts also limits an attacker's ability to obtain the local execution this flaw requires, though none of these controls substitutes for installing the fixed builds.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 6 packages in euvd
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
The root cause is CWE-416 (Use After Free), a memory-safety class in which an object in the Windows hypervisor's memory pool is released and then dereferenced, so a subsequent allocation can occupy the freed region and be consumed as attacker-influenced data. Hyper-V exposes a large local attack surface through the virtual machine bus (VMBus), hypercall interfaces, virtual service providers and virtual device stacks; a process on a host with the Hyper-V role or related virtualization features enabled can interact with these paths and influence the allocation/free ordering that produces the dangling reference. Because the corrupted object is later consumed in a privileged context, successful reuse converts a low-privileged local process into host kernel/SYSTEM-level execution, which is why the assessed impact is total across confidentiality, integrity and availability. The attack is not remotely reachable (AV:L), needs no user interaction (UI:N) and has low complexity (AC:L), but presupposes PR:L - an existing authenticated local foothold - and the Hyper-V role being present on the target. Per the independent assessment, hosts without Hyper-V enabled are not affected, and builds at or above the fixed versions are not vulnerable.
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Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local hypervisor UAF needs an existing low-priv local foothold (AV:L/PR:L), triggers without interaction (AC:L/UI:N), yielding total host impact (C:H/I:H/A:H).
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Use after free in Windows Hyper-V allows an authorized attacker to elevate privileges locally.
Executive ViewAI
A high-severity local privilege escalation vulnerability in Microsoft Windows Hyper-V affects Windows 11 versions 24H2, 25H2, 26H1, and 26H2 as well as Windows Server 2025, allowing an authenticated local user to gain SYSTEM-level privileges on Hyper-V-enabled hosts. Organizations using Hyper-V for virtualization or multi-user environments should prioritize patching because successful exploitation could compromise host integrity and expose sensitive workloads. Patch available per vendor advisory, and no public exploit identified at time of analysis.
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Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
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
Use-after-free vulnerabilities occur when a program continues to access memory through a pointer after that memory has been deallocated.
Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.
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