CVE-2019-1309 — Windows Hyper-V Denial of Service Vulnerability

Executive Summary

A denial of service vulnerability exists when Microsoft Hyper-V Network Switch on a host server fails to properly validate input from a privileged user on a guest operating system. An attacker who successfully exploited the vulnerability could cause the host server to crash. 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 that causes a host machine to crash. The update addresses the vulnerability by modifying how virtual machines access the Hyper-V Network Switch.

Overview

6.8

CVSS MEDIUM

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Denial of Service

Released Nov 12 2019

Last Updated Nov 12 2019

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.05141 — 0.91532 percentile

NVD CVSS 6.8 MEDIUM — differs from MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C

ATTACK VECTOR

Network

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

High

USER INTERACTION

None

SCOPE

Changed

CONFIDENTIALITY

None

INTEGRITY

None

AVAILABILITY

High

EXPLOIT CODE MATURITY

Proof-of-Concept

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 5.2

EPSS Score

0.05141

probability of exploitation in the next 30 days

0.91532 percentile - updated 2026-07-25

View on FIRST.org

Affected Products

8 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1709 for x64-based Systems	`4525241 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1803 for x64-based Systems	`4525237 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1809 for x64-based Systems	`4523205 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1903 for x64-based Systems	`4524570 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2019	`4523205 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2019 (Server Core installation)	`4523205 (Security Update)`	Important	Denial of Service	Yes
Windows Server, version 1803 (Server Core Installation)	`4525237 (Security Update)`	Important	Denial of Service	Yes
Windows Server, version 1903 (Server Core installation)	`4524570 (Security Update)`	Important	Denial of Service	Yes

Patches

4 patches

Article	Type	Restart
`4525241`	Security Update	Yes
`4525237`	Security Update	Yes
`4523205`	Security Update	Yes
`4524570`	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

HongZhenhao of IceSword Lab, Qihoo 360

References

MSRC Advisory MITRE NVD