Windows
CVE-2025-21333
HIGH
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A06:2021 - Vulnerable and Outdated Components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. |
| Impact | High risk (CVSS 7.8, EPSS 81.8%). Three simultaneous Hyper-V zero-days indicate a sophisticated attacker targeting virtualized infrastructure. Hyper-V VSP vulnerabilities can potentially enable guest-to-host escape. |
| Exploit ScenarioDerived | An attacker in a Hyper-V guest VM exploits the VSP heap overflow to corrupt host kernel memory, escalating from the VM sandbox to the Hyper-V host with SYSTEM privileges, potentially compromising all other VMs on the same host. |
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Alert meAnalysisAIv1 – Mar 28, 2026
Windows Hyper-V NT Kernel Integration VSP contains a heap-based buffer overflow allowing authorized local attackers to escalate privileges, one of three Hyper-V zero-days exploited in January 2025 Patch Tuesday.
Earlier versions of this analysis (1)
A heap-based buffer overflow in Windows Hyper-V NT Kernel Integration VSP enables local privilege escalation. Part of a triple Hyper-V zero-day set (with CVE-2025-21334 and CVE-2025-21335) exploited in the wild.
RemediationAI
Apply January 2025 Patch Tuesday updates. Monitor Hyper-V hosts for anomalous behavior. Consider isolating high-security workloads on dedicated hosts.
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
The CWE-122 heap overflow in the VSP (Virtual Service Provider) component of Hyper-V's NT Kernel Integration allows local attackers to corrupt heap memory and escalate privileges from guest VM or local user context.
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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:N/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
Lifecycle Timeline
4DescriptionCVE.org
Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability
Executive ViewAI
CVE-2025-21333 presents notable security risk, a heap-based buffer overflow vulnerability rated CVSS 7.8. Exploitation could allow attackers to corrupt memory, crash the application, or potentially execute arbitrary code. This vulnerability is actively exploited in the wild (KEV-listed) and requires immediate remediation. A patch is available and should be applied as part of regular vulnerability management.
Apply vendor patch. If immediate patching is not feasible: (1) Enable ASLR and DEP where available; (2) Implement network segmentation; (3) Monitor for exploitation indicators.
Threat Intelligence Overview
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.
Affected Products (CPE)CVE.org
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GitHub PoC
Exploit-DB