CVE-2019-1399 — 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 input from a privileged 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 that causes a host machine 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. The security update addresses the vulnerability by resolving a number of conditions where Hyper-V would fail to prevent a guest operating system from sending malicious requests.

Overview

6.2

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 0.01597 — 0.73229 percentile

NVD CVSS 6.2 MEDIUM — differs from MSRC

CVSS Vector

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

ATTACK VECTOR

Adjacent_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: 4.9

EPSS Score

0.01597

probability of exploitation in the next 30 days

0.73229 percentile - updated 2026-07-25

View on FIRST.org

Affected Products

11 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1607 for x64-based Systems	`4525236 (Security Update)`	Important	Denial of Service	Yes
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 7 for x64-based Systems Service Pack 1 4525235 (Monthly Rollup) 4525233 (Security Only) Important Denial of Service 4519976 Base: 5.4 Temporal: 4.9 Vector: CVSS:3.0/AV:A/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C Yes None Windows 8.1 for x64-based systems 4525243 (Monthly Rollup) 4525250 (Security Only) Important Denial of Service 4520005 Base: 5.4 Temporal: 4.9 Vector: CVSS:3.0/AV:A/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C Yes None Windows Server 2008 for x64-based Systems Service Pack 2 4525234 (Monthly Rollup) 4525239 (Security Only) Important Denial of Service 4520002 Base: 5.4 Temporal: 4.9 Vector: CVSS:3.0/AV:A/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C Yes None Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) 4525234 (Monthly Rollup) 4525239 (Security Only) Important Denial of Service 4520002 Base: 5.4 Temporal: 4.9 Vector: CVSS:3.0/AV:A/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C Yes None Windows Server 2008 R2 for x64-based Systems Service Pack 1 4525235 (Monthly Rollup) 4525233 (Security Only) Important Denial of Service 4519976 Base: 5.4 Temporal: 4.9 Vector: CVSS:3.0/AV:A/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C Yes None Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) 4525235 (Monthly Rollup) 4525233 (Security Only) Important Denial of Service 4519976 Base: 5.4 Temporal: 4.9 Vector: CVSS:3.0/AV:A/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C Yes None Windows Server 2012 4525246 (Monthly Rollup) 4525253 (Security Only) Important Denial of Service 4520007 4519985 Base: 5.4 Temporal: 4.9 Vector: CVSS:3.0/AV:A/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C Yes None Windows Server 2012 (Server Core installation) 4525246 (Monthly Rollup) 4525253 (Security Only) Important Denial of Service 4520007 4519985 Base: 5.4 Temporal: 4.9 Vector: CVSS:3.0/AV:A/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C Yes None Windows Server 2012 R2 4525243 (Monthly Rollup) 4525250 (Security Only) Important Denial of Service 4520005 Base: 5.4 Temporal: 4.9 Vector: CVSS:3.0/AV:A/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C Yes None Windows Server 2012 R2 (Server Core installation) 4525243 (Monthly Rollup) 4525250 (Security Only) Important Denial of Service 4520005 Base: 5.4 Temporal: 4.9 Vector: CVSS:3.0/AV:A/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C Yes None Windows Server 2016	`4525236 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2016 (Server Core installation)	`4525236 (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 1709 (Server Core Installation) Important Denial of Service None Base: 5.4 Temporal: 4.9 Vector: CVSS:3.0/AV:A/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C Unknown Unknown None 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

5 patches

Article	Type	Restart
`4525236`	Security Update	Yes
`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

Microsoft Virtualization Security Team

References

MSRC Advisory MITRE NVD