CVE-2026-83766

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Incorrect Authorization Bypass in Windows Hyper-V

Publication date: 2026-10-13

Last updated on: 2026-10-16

Assigner: Microsoft Corporation

Description

Incorrect authorization in Windows Hyper-V allows an authorized attacker to bypass a security feature over an adjacent network.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-10-13

Last Modified

2026-10-16

Generated

2026-10-19

AI Q&A

2026-10-14

EPSS Evaluated

2026-10-18

NVD

CVE-2026-83766

EUVD

EUVD-2026-99987

Affected Vendors & Products

Vendor	Product	Version / Range
Microsoft	Windows	10 Version 1607 10.0.14393.0
Microsoft	Windows	10 Version 1809 10.0.17763.0
Microsoft	Windows	10 Version 21H2 10.0.19044.0
Microsoft	Windows	10 Version 22H2 10.0.19045.0
Microsoft	Windows	11 version 23H2 10.0.22631.0
Microsoft	Windows	11 Version 23H2 10.0.22631.0
Microsoft	Windows	11 Version 24H2 10.0.26100.0
Microsoft	Windows	11 Version 25H2 10.0.26200.0
Microsoft	Windows	11 version 26H1 10.0.28000.0
Microsoft	Windows	11 Version 26H2 10.0.26300.0
Microsoft	Windows	Server 2016 10.0.14393.0
Microsoft	Windows	Server 2016 (Server Core installation) 10.0.14393.0
Microsoft	Windows	Server 2019 10.0.17763.0
Microsoft	Windows	Server 2019 (Server Core installation) 10.0.17763.0
Microsoft	Windows	Server 2022 10.0.20348.0
Microsoft	Windows	Server 2025 10.0.26100.0
Microsoft	Windows	Server 2025 (Server Core installation) 10.0.26100.0

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-863	The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

Attack-Flow Graph

Executive Summary

This vulnerability involves incorrect authorization in Windows Hyper-V. An authorized attacker can bypass a security feature by exploiting it over an adjacent network.

Impact Analysis

An attacker could gain unauthorized access to systems or data by bypassing security controls in Hyper-V. This may lead to data breaches or unauthorized system modifications.

Compliance Impact

This vulnerability allows bypassing a security feature in Windows Hyper-V, which could lead to unauthorized access or data exposure. Such breaches may violate compliance requirements under GDPR (data protection) and HIPAA (health data security) by failing to maintain adequate security controls.

Mitigation Strategies

Apply the latest security updates from Microsoft to address the Hyper-V authorization issue. Monitor Microsoft's advisory for patches and install them promptly.

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