---
title: "CVE-2025-21333: Microsoft Windows Hyper-V NT Kernel Integration VSP Heap-based Buffer Overflow Vulnerability"
url: https://erroneo.us/security/cve/CVE-2025-21333/
description: "CVE-2025-21333 (Microsoft Windows): Exploited in the wild (CISA KEV). Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability"
type: vulnerability-record
section: "Security Digest"
date_published: 2025-01-14
date_modified: 2026-06-09
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2025-21333"
kev: true
cvss: 7.8
epss: 0.10066
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2025-21333: Microsoft Windows Hyper-V NT Kernel Integration VSP Heap-based Buffer Overflow Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run Microsoft Windows. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2025-01-14, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2025-02-04 ; treat that as the outer limit, not the target.
- EPSS 10.1% , percentile 96: FIRST’s model estimates a 10.1% chance of exploitation activity in the next 30 days, higher than 96% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Needs local access needed. Lower urgency for most teams unless an attacker could already run code on the machine.

## What it is

Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability

## Affected products (CVE record)

- Microsoft Windows 10 Version 21H2: 10.0.19044.0 < 10.0.19044.5371
- Microsoft Windows 10 Version 22H2: 10.0.19045.0 < 10.0.19045.5371
- Microsoft Windows 11 version 22H2: 10.0.22621.0 < 10.0.22621.4751
- Microsoft Windows 11 version 22H3: 10.0.22631.0 < 10.0.22631.4751
- Microsoft Windows 11 Version 23H2: 10.0.22631.0 < 10.0.22631.4751
- Microsoft Windows 11 Version 24H2: 10.0.26100.0 < 10.0.26100.2894
- Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): 10.0.25398.0 < 10.0.25398.1369
- Microsoft Windows Server 2025: 10.0.26100.0 < 10.0.26100.2894
- Microsoft Windows Server 2025 (Server Core installation): 10.0.26100.0 < 10.0.26100.2894

## Severity

- microsoft CVSS 3.1: 7.8 `CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C`

## Exploitation

- CISA KEV: added 2025-01-14; federal due date 2025-02-04. Known ransomware use: Unknown.
- CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- CISA SSVC assessment: exploitation active , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 10.07% probability of exploitation activity in the next 30 days; percentile 96.

## Sources

- [Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21333)
- [Listed in CISA KEV notes (msrc.microsoft.com)](https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2025-21333)
- [CVE.org record CVE-2025-21333](https://www.cve.org/CVERecord?id=CVE-2025-21333)
- [NVD entry CVE-2025-21333](https://nvd.nist.gov/vuln/detail/CVE-2025-21333)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21333)
- [vicarius.io](https://www.vicarius.io/vsociety/posts/cve-2025-21333-elevated-privilege-exposure-in-windows-hyper-v-by-microsoft-mitigation-script)
- [vicarius.io](https://www.vicarius.io/vsociety/posts/cve-2025-21333-elevated-privilege-exposure-in-windows-hyper-v-by-microsoft-detection-script)
- [exploit-db.com](https://www.exploit-db.com/exploits/52436)

---
Source page: https://erroneo.us/security/cve/CVE-2025-21333/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt