Windows Hyper-V
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
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C
ATTACK VECTOR
Local
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
Low
USER INTERACTION
None
SCOPE
Unchanged
CONFIDENTIALITY
High
INTEGRITY
High
AVAILABILITY
High
EXPLOIT CODE MATURITY
Proof-of-Concept
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 7.0
EPSS Score
0.009
probability of exploitation in the next 30 days
0.55984 percentile - updated 2026-07-25
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
Nicolas Economou from Blue Frost Security
References
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