OnlyFm252
Role: Windows Hyper-V

CVE-2021-28476 — Windows Hyper-V Remote Code Execution Vulnerability

Critical CVSS 9.9 EPSS 0.39226 2021-05 archive

Executive Summary

None

Overview

9.9
CVSS CRITICAL
Critical
MS Severity
Not Exploited
MS Exploit Status
Less Likely
MS Exploit Likelihood
Category Remote Code Execution
Released May 11 2021
Last Updated May 11 2021
Publicly Disclosed No
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.39226 — 0.98414 percentile
NVD CVSS 9.9 CRITICAL — matches MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
ATTACK VECTOR
Network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
Low
USER INTERACTION
None
SCOPE
Changed
CONFIDENTIALITY
High
INTEGRITY
High
AVAILABILITY
High
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 8.6

EPSS Score

0.39226
probability of exploitation in the next 30 days
0.98414 percentile - updated 2026-06-21
View on FIRST.org

Affected Products

13 affected products
Product KB Article Severity Impact Restart Required
Windows 10 for x64-based Systems 5003172 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 1607 for x64-based Systems 5003197 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 1803 for x64-based Systems 5003174 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 1809 for x64-based Systems 5003171 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 1909 for x64-based Systems 5003169 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 2004 for x64-based Systems 5003173 (Security Update) Critical Remote Code Execution Yes
Windows 7 for x64-based Systems Service Pack 1 5003233 (Monthly Rollup) 5003228 (Security Only) Critical Remote Code Execution 5001335 5001392 Base: 9.9 Temporal: 8.6 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C 6.1.7601.24597 6.1.7601.24598 Yes 5003233 5003228 Windows 8.1 for x64-based systems 5003209 (Monthly Rollup) 5003220 (Security Only) Critical Remote Code Execution 5001382 5001383 Base: 9.9 Temporal: 8.6 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C 6.3.9600.20017 Yes 5003209 5003220 Windows Server 2008 for x64-based Systems Service Pack 2 5003210 (Monthly Rollup) 5003225 (Security Only) Critical Remote Code Execution 5001389 5001332 Base: 9.9 Temporal: 8.6 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C 6.0.6003.21117 Yes 5003210 5003225 Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) 5003210 (Monthly Rollup) 5003225 (Security Only) Critical Remote Code Execution 5001389 5001332 Base: 9.9 Temporal: 8.6 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C 6.0.6003.21117 Yes 5003210 5003225 Windows Server 2008 R2 for x64-based Systems Service Pack 1 5003233 (Monthly Rollup) 5003228 (Security Only) Critical Remote Code Execution 5001335 5001392 Base: 9.9 Temporal: 8.6 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C 6.1.7601.24597 6.1.7601.24598 Yes 5003233 5003228 Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) 5003233 (Monthly Rollup) 5003228 (Security Only) Critical Remote Code Execution 5001335 5001392 Base: 9.9 Temporal: 8.6 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C 6.1.7601.24597 6.1.7601.24598 Yes 5003233 5003228 Windows Server 2012 5003208 (Monthly Rollup) 5003203 (Security Only) Critical Remote Code Execution 5001387 5001383 Base: 9.9 Temporal: 8.6 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C 6.2.9200.23347 Yes 5003208 5003203 Windows Server 2012 (Server Core installation) 5003208 (Monthly Rollup) 5003203 (Security Only) Critical Remote Code Execution 5001387 5001383 Base: 9.9 Temporal: 8.6 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C 6.2.9200.23347 Yes 5003208 5003203 Windows Server 2012 R2 5003209 (Monthly Rollup) 5003220 (Security Only) Critical Remote Code Execution 5001382 5001383 Base: 9.9 Temporal: 8.6 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C 6.3.9600.20017 Yes 5003209 5003220 Windows Server 2012 R2 (Server Core installation) 5003209 (Monthly Rollup) 5003220 (Security Only) Critical Remote Code Execution 5001382 5001383 Base: 9.9 Temporal: 8.6 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C 6.3.9600.20017 Yes 5003209 5003220 Windows Server 2016 5003197 (Security Update) Critical Remote Code Execution Yes
Windows Server 2016 (Server Core installation) 5003197 (Security Update) Critical Remote Code Execution Yes
Windows Server 2019 5003171 (Security Update) Critical Remote Code Execution Yes
Windows Server 2019 (Server Core installation) 5003171 (Security Update) Critical Remote Code Execution Yes
Windows Server, version 1909 (Server Core installation) 5003169 (Security Update) Critical Remote Code Execution Yes
Windows Server, version 2004 (Server Core installation) 5003173 (Security Update) Critical Remote Code Execution Yes
Windows Server, version 20H2 (Server Core Installation) 5003173 (Security Update) Critical Remote Code Execution Yes

Patches

6 patches
Article Type Restart
5003172 Security Update Yes
5003197 Security Update Yes
5003174 Security Update Yes
5003171 Security Update Yes
5003169 Security Update Yes
5003173 Security Update Yes

Known Exploits

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