CVE-2020-1243 — Windows Hyper-V Denial of Service Vulnerability

Executive Summary

A denial of service vulnerability exists when Microsoft Hyper-V on a host server fails to properly validate specific malicious data from a user on a guest operating system. To exploit the vulnerability, an attacker who already has a privileged account on a guest operating system, running as a virtual machine, could run a specially crafted application. The security update addresses the vulnerability by resolving the conditions where Hyper-V would fail to handle these requests.

Overview

7.8

CVSS HIGH

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Denial of Service

Released Oct 13 2020

Last Updated Oct 13 2020

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.00885 — 0.54493 percentile

CVSS Vector

ATTACK VECTOR

Local

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

Low

USER INTERACTION

None

SCOPE

Unchanged

Temporal Score: 7.0

EPSS Score

0.00885

probability of exploitation in the next 30 days

0.54493 percentile - updated 2026-06-20

View on FIRST.org

Affected Products

14 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1607 for x64-based Systems	`4580346 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1709 for x64-based Systems	`4580328 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1803 for x64-based Systems	`4580330 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1809 for x64-based Systems	`4577668 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1903 for x64-based Systems	`4577671 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1909 for x64-based Systems	`4577671 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 2004 for x64-based Systems	`4579311 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2016	`4580346 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2016 (Server Core installation)	`4580346 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2019	`4577668 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2019 (Server Core installation)	`4577668 (Security Update)`	Important	Denial of Service	Yes
Windows Server, version 1903 (Server Core installation)	`4577671 (Security Update)`	Important	Denial of Service	Yes
Windows Server, version 1909 (Server Core installation)	`4577671 (Security Update)`	Important	Denial of Service	Yes
Windows Server, version 2004 (Server Core installation)	`4579311 (Security Update)`	Important	Denial of Service	Yes

Patches

6 patches

Article	Type	Restart
`4580346`	Security Update	Yes
`4580328`	Security Update	Yes
`4580330`	Security Update	Yes
`4577668`	Security Update	Yes
`4577671`	Security Update	Yes
`4579311`	Security Update	Yes

Known Exploits

No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.

Acknowledgments

Blue Frost Security

References

MSRC Advisory MITRE NVD