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8.8
HIGH CVSS 3.1
CVE-2026-21255
Windows Hyper-V Security Feature Bypass Vulnerability
Description

Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.

INFO

Published Date :

Feb. 10, 2026, 6:16 p.m.

Last Modified :

Feb. 10, 2026, 9:51 p.m.

Remotely Exploit :

No

Source :

[email protected]
Affected Products

The following products are affected by CVE-2026-21255 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Microsoft windows_server_2016
2 Microsoft windows_server_2019
3 Microsoft windows_10_1607
4 Microsoft windows_10_1809
5 Microsoft windows_10_21h2
6 Microsoft windows_10_22h2
7 Microsoft windows_server_2022
8 Microsoft windows_11_23h2
9 Microsoft windows_server_23h2
10 Microsoft windows_11_24h2
11 Microsoft windows_server_2025
12 Microsoft windows_11_25h2
13 Microsoft windows_11_26h1
: Total Affected Vendor : 1 | Products : 13
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 HIGH [email protected]
Solution
Address improper access control by applying security updates to Windows Hyper-V.
  • Apply Windows Hyper-V security updates.
  • Review and enforce access control policies.
  • Limit local administrative privileges.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-21255.

URL Resource
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21255
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-21255 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-21255 weaknesses.

CAPEC-19: Embedding Scripts within Scripts Embedding Scripts within Scripts CAPEC-441: Malicious Logic Insertion Malicious Logic Insertion CAPEC-478: Modification of Windows Service Configuration Modification of Windows Service Configuration CAPEC-479: Malicious Root Certificate Malicious Root Certificate CAPEC-502: Intent Spoof Intent Spoof CAPEC-503: WebView Exposure WebView Exposure CAPEC-536: Data Injected During Configuration Data Injected During Configuration CAPEC-546: Incomplete Data Deletion in a Multi-Tenant Environment Incomplete Data Deletion in a Multi-Tenant Environment CAPEC-550: Install New Service Install New Service CAPEC-551: Modify Existing Service Modify Existing Service CAPEC-552: Install Rootkit Install Rootkit CAPEC-556: Replace File Extension Handlers Replace File Extension Handlers CAPEC-558: Replace Trusted Executable Replace Trusted Executable CAPEC-562: Modify Shared File Modify Shared File CAPEC-563: Add Malicious File to Shared Webroot Add Malicious File to Shared Webroot CAPEC-564: Run Software at Logon Run Software at Logon CAPEC-578: Disable Security Software Disable Security Software

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-21255 vulnerability anywhere in the article.

  • The Cyber Express
Microsoft Patch Tuesday February Update Flags Exchange and Azure Vulnerabilities as High-Priority Risks

Microsoft Patch Tuesday February 2026 addressed 54 vulnerabilities including six zero-days across Windows, Office, Azure services, Exchange Server, and developer tools. The latest patch update, rollou ... Read more

Published Date: Feb 11, 2026 (4 hours, 51 minutes ago)
  • Zero Day Initiative
The February 2026 Security Update Review

I have survived the biggest Pwn2Own ever, but I’m back in Tokyo for the second Patch Tuesday of 2026. My location never stops Patch Tuesday from coming, so let’s take a look at the latest security pat ... Read more

Published Date: Feb 10, 2026 (17 hours, 5 minutes ago)
  • CybersecurityNews
Microsoft Patch Tuesday February 2026 – 54 Vulnerabilities Fixed, Including 6 Zero-days

Microsoft Patch Tuesday February 2026 Microsoft released its February 2026 Patch Tuesday updates on February 10, addressing 54 vulnerabilities, including six zero-days across Windows, Office, Azure, a ... Read more

Published Date: Feb 10, 2026 (17 hours, 24 minutes ago)

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-21255 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • New CVE Received by [email protected]

    Feb. 10, 2026

    Action Type Old Value New Value
    Added Description Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.
    Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
    Added CWE CWE-284
    Added Reference https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21255
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 8.8
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact