CVE-2026-20825: Microsoft Windows Hyper-V improper access control information disclosure

CVE-2026-20825 · Severity: medium · CVSS 4.4 · Published 2026-01-13

A security vulnerability exists in Microsoft Hyper-V, the virtualization technology used to run multiple operating systems on a single physical server. An authorized user with high-level privileges on the system could exploit this flaw to access sensitive information that should otherwise be restricted. While this could lead to data exposure, the attacker must already have significant access to the local machine to perform the exploit.

Technologies: Microsoft Hyper-V, Microsoft Windows 11, Microsoft Windows 10, Microsoft Windows 10 1809, Microsoft Windows 10 21h2, Microsoft Windows 10 22h2, Microsoft Windows 11 23h2, Microsoft Windows 11 24h2, Microsoft Windows 11 25h2, Microsoft Windows Server 2019, Microsoft Windows Server 2022, Microsoft Windows Server 2022 23h2, Microsoft Windows Server 2025. Vendors: Microsoft.

Quick answers

Is CVE-2026-20825 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-20825 being exploited in the wild.
How severe is CVE-2026-20825?
Medium severity, with a CVSS score of 4.4, published 13 January 2026.
Which products and versions are affected?
Microsoft Hyper-V All versions; Microsoft Windows 11 22H3, 23H2, 24H2, 25H2; Microsoft Windows 10 1809, 21H2, 22H2; Microsoft Windows Server 2019 All versions; and 1 more.
Is there a fix for CVE-2026-20825?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-20825 attacked?
It is attacked with local access, in an operating system.
Am I affected by CVE-2026-20825?
Check whether you run Microsoft Hyper-V, Microsoft Windows 11, Microsoft Windows 10 or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An information disclosure vulnerability exists in Windows Hyper-V due to improper access control (CWE-284). The flaw allows a local attacker with high privileges (PR:H) to bypass security restrictions and access sensitive data within the virtualization environment. The attack vector is local, meaning the attacker must have direct access to the host or a highly privileged position within the environment. Microsoft has released security updates to address this issue across various versions of Windows 10, Windows 11, and Windows Server. Security engineers should apply the relevant cumulative updates for their specific OS build.

Affected products

  • Microsoft Windows 10 1809, 21H2, 22H2
  • Microsoft Windows 11 22H3, 23H2, 24H2, 25H2
  • Microsoft Windows Server 2019 All versions
  • Microsoft Windows Server 2022 All versions
  • Microsoft Windows Hyper-V All versions

Timeline

  • 2026-01-13: advisory: Initial disclosure by Microsoft and NVD
  • 2026-07-30: other: CVE record modified by Microsoft

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.