CVE-2021-43246

Host service interruption via undisclosed Hyper-V flaw

Published Dec 15, 2021 · Updated Aug 4, 2024

Denial of service in Microsoft Windows Hyper-V allows local users with low privileges to interrupt host availability via an undisclosed vector. Microsoft has not published the vulnerable Hyper-V code path or the operation it performs incorrectly. Exploitation requires local low-privilege access and high-complexity conditions, and the published impact is limited to service interruption.

CVSS severity5.6
Medium
EPSS probability0.75%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Microsoft Windows Hyper-V allows local users with low privileges to interrupt host availability via an undisclosed vector. Microsoft has not published the vulnerable Hyper-V code path or the operation it performs incorrectly. Exploitation requires local low-privilege access and high-complexity conditions, and the published impact is limited to service interruption.

The record

CVE
CVE-2021-43246
Published
Dec 15, 2021
Updated
Aug 4, 2024
Vendor
Microsoft
Product
Windows Server 2019
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0.0 <10.0.17763.2366

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Windows Server 2019version=10.0.0 <10.0.17763.2366
Microsoft · Windows 10 Version 21H1version=10.0.0 <10.0.19043.1415
Microsoft · Windows 10 Version 1909version=10.0.0 <10.0.18363.1977
Microsoft · Windows 11 version 21H2version=10.0.0 <10.0.22000.376
Microsoft · Windows Server, version 2004version=10.0.0 <10.0.19041.1415
Microsoft · Windows 10 Version 21H2version=10.0.0 <10.0.19044.1415
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.0 <10.0.17763.2366
Microsoft · Windows Server version 20H2version=10.0.0 <10.0.19042.1415
Microsoft · Windows Server 2022version=10.0.0 <10.0.20348.405
Microsoft · Windows 10 Version 2004version=10.0.0 <10.0.19041.1415
Microsoft · Windows 10 Version 1809version=10.0.0 <10.0.17763.2366

Published CVSS scores

4.9NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:C
5.6Microsoft CorporationCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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