CVE-2021-28476
published 2021-05-11CVE-2021-28476: Windows Hyper-V Remote Code Execution Vulnerability
PriorityP275critical9.9CVSS 3.1
AVNACLPRLUINSCCHIHAH
EPSS
38.63%
98.4th percentile
Windows Hyper-V Remote Code Execution Vulnerability
Affected
47 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| microsoft | windows_10 | — | — |
| microsoft | windows_10 | — | — |
| microsoft | windows_10 | — | — |
| microsoft | windows_10 | — | — |
| microsoft | windows_10 | — | — |
| microsoft | windows_10 | — | — |
| microsoft | windows_10_version_1507 | >= 10.0.0 < 10.0.10240.18931 | 10.0.10240.18931 |
| microsoft | windows_10_version_1607 | >= 10.0.0 < 10.0.14393.4401 | 10.0.14393.4401 |
| microsoft | windows_10_version_1803 | >= 10.0.0 < 10.0.17134.2207 | 10.0.17134.2207 |
| microsoft | windows_10_version_1809 | >= 10.0.0 < 10.0.17763.1935 | 10.0.17763.1935 |
| microsoft | windows_10_version_1909 | >= 10.0.0 < 10.0.18363.1556 | 10.0.18363.1556 |
| microsoft | windows_10_version_2004 | >= 10.0.0 < 10.0.19041.982 | 10.0.19041.982 |
| microsoft | windows_7_service_pack_1 | >= 6.1.0 < 6.1.7601.24597 | 6.1.7601.24597 |
| microsoft | windows_7_service_pack_1 | >= 6.1.0 < 6.1.7601.24598 | 6.1.7601.24598 |
| microsoft | windows_8.1 | >= 6.3.0 < 6.3.9600.20017 | 6.3.9600.20017 |
| microsoft | windows_server_2008 | — | — |
| microsoft | windows_server_2008_r2_service_pack_1 | >= 6.0.0 < 6.1.7601.24597 | 6.1.7601.24597 |
| microsoft | windows_server_2008_r2_service_pack_1 | >= 6.0.0 < 6.1.7601.24598 | 6.1.7601.24598 |
| microsoft | windows_server_2008_r2_service_pack_1 | >= 6.1.0 < 6.1.7601.24597 | 6.1.7601.24597 |
| microsoft | windows_server_2008_r2_service_pack_1 | >= 6.1.0 < 6.1.7601.24598 | 6.1.7601.24598 |
| microsoft | windows_server_2008_service_pack_2 | >= 6.0.0 < 6.0.6003.21117 | 6.0.6003.21117 |
| microsoft | windows_server_2012 | — | — |
| microsoft | windows_server_2012 | >= 6.2.0 < 6.2.9200.23347 | 6.2.9200.23347 |
| microsoft | windows_server_2012_r2 | >= 6.3.0 < 6.3.9600.20017 | 6.3.9600.20017 |
| microsoft | windows_server_2016 | — | — |
Detection & IOCsextracted from sources · hover to see the quote
- →A guest VM can force the Hyper-V host's kernel to read from an arbitrary, potentially invalid address — monitor for unexpected Hyper-V host bugchecks (kernel crashes) originating from guest VM activity as a sign of exploitation attempts. ↗
- →Exploitation may trigger hardware device-specific side effects via memory-mapped device registers — monitor for anomalous hardware device behaviour on Hyper-V hosts that correlates with guest VM network activity. ↗
- ·The vulnerability affects the Windows Hyper-V role specifically; exploitation requires the attacker to control a guest VM on the target Hyper-V host. ↗
- ·Microsoft assessed exploitation as 'Less Likely' for both latest and older software releases at time of disclosure, and confirmed no known in-the-wild exploitation. ↗
CVSS provenance
nvdv3.19.9CRITICALCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
nvdv2.06.5MEDIUMAV:N/AC:L/Au:S/C:P/I:P/A:P
vendor_msrc9.9CRITICAL
Stop checking back — get the weekly exploitation signal.
Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.
No detection rules found.
No public exploits indexed.
Checkpoint
2nd August – Threat Intelligence Report
blogs_checkpoint·2021-08-02
CVE-2021-30807 2nd August – Threat Intelligence Report
Latest Publications
CPR Podcast Channel
AI Research
Web 3.0 Security
Intelligence Reports
ThreatCloud AI
Threat Intelligence & Research
Zero Day Protection
Sandblast File Analysis
About Us
SUBSCRIBE
2026
2025
2024
2023
2022
2021
2020
2019
2018
2017
2016
## 2nd August – Threat Intelligence Report
For the latest discoveries in cyber research for the week of 2nd August, please download our Threat Intelligence Bulletin .
Top Attacks and Breaches
The company that manages COVID-19 vaccination appointments in the Lazio Region in Italy has been hit by ransomware. The attack took down its IT systems, making the booking site unreachable and suspending the vaccination of the entire region surrounding Rome.
Check Point Harmony Endpoint provides protection against this threa
Tenable
Microsoft’s May 2021 Patch Tuesday Addresses 55 CVEs (CVE-2021-31166)
blogs_tenable·2021-05-11·CVSS 9.8
[CRITICAL] Microsoft’s May 2021 Patch Tuesday Addresses 55 CVEs (CVE-2021-31166)
## Cloud Exposure
Tenable Cloud Security (CNAPP) Request a demo
Tenable Cloud Vulnerability Management Request a demo
Tenable CIEM Request a demo
Secure your cloud
## Vulnerability Exposure
Tenable Vulnerability Management Try for free
Tenable Security Center Request a demo
Tenable Web App Scanning Try for free
Tenable Patch Management Request a demo
Tenable Enclave Security Request a demo
Tenable Attack Surface Management Request a demo
Tenable Nessus Try for free
## AI Exposure
Tenable AI Exposure Request a demo
## OT/IoT Exposure
Tenable OT Security Request a demo
## Identity Exposure
Tenable Identity Exposure Request a demo
## Business needs
Active Directory
AI Security Posture Management (AI-SPM)
AWS security
Azure security
Cloud Security Posture Man
Qualys
Microsoft & Adobe Patch Tuesday (May 2021) – Qualys covers 85 Vulnerabilities, 26 Critical
blogs_qualys·2021-05-11·CVSS 9.9
CVE-2021-31181 [CRITICAL] Microsoft & Adobe Patch Tuesday (May 2021) – Qualys covers 85 Vulnerabilities, 26 Critical
## Microsoft Patch Tuesday – May 2021
Microsoft patched 55 CVEs in their May 2021 Patch Tuesday release, of which 4 are rated as critical severity. Three 0-day vulnerability patches were included in the release. As of this publication date, none have been exploited.
Qualys released 12 QIDs on the same day, providing vulnerability detection and patch management coverage (where applicable) for all 55 CVEs and the related KBs.
## Critical Microsoft vulnerabilities patched:
CVE-2021-31181 – SharePoint Remote Code Execution Vulnerability
Microsoft released patches addressing a critical RCE vulnerability in SharePoint (CVE-2021-31181). This CVE has a high likelihood of exploitability and is assigned a CVSSv3 base score of 8.8 by the vendor.
CVE-2021-31166 – HTTP Protocol Stack Remote Code
Qualys
Microsoft & Adobe Patch Tuesday (May 2021) - Qualys covers 85 Vulnerabilities, 26 Critical | Qualys
blogs_qualys·2021-05-11·CVSS 9.9
CVE-2021-31181 [CRITICAL] Microsoft & Adobe Patch Tuesday (May 2021) - Qualys covers 85 Vulnerabilities, 26 Critical | Qualys
### Microsoft Patch Tuesday – May 2021
Microsoft patched 55 CVEs in their May 2021 Patch Tuesday release, of which 4 are rated as critical severity. Three 0-day vulnerability patches were included in the release. As of this publication date, none have been exploited.
Qualys released 12 QIDs on the same day, providing vulnerability detection and patch management coverage (where applicable) for all 55 CVEs and the related KBs.
#### Critical Microsoft vulnerabilities patched:
CVE-2021-31181 – SharePoint Remote Code Execution Vulnerability
Microsoft released patches addressing a critical RCE vulnerability in SharePoint (CVE-2021-31181). This CVE has a high likelihood of exploitability and is assigned a CVSSv3 base score of 8.8 by the vendor.
CVE-2021-31166 – HTTP Protocol Stack Remote Co
Crowdstrike
May 2021 Patch Tuesday: Updates and Analysis
blogs_crowdstrike·CVSS 7.5
CVE-2026-20929 [HIGH] May 2021 Patch Tuesday: Updates and Analysis
STARDUST CHOLLIMA Likely Compromises Axios npm Package Apr 01, 2026
Falcon for IT Supports Windows Secure Boot Certificate Lifecycle Management Apr 01, 2026
Detecting CVE-2026-20929: Kerberos Authentication Relay via CNAME Abuse Mar 31, 2026
How Charlotte AI AgentWorks Fuels Security's Agentic Ecosystem Mar 25, 2026
STARDUST CHOLLIMA Likely Compromises Axios npm Package Apr 01, 2026
Falcon for IT Supports Windows Secure Boot Certificate Lifecycle Management Apr 01, 2026
Detecting CVE-2026-20929: Kerberos Authentication Relay via CNAME Abuse Mar 31, 2026
How Charlotte AI AgentWorks Fuels Security's Agentic Ecosystem Mar 25, 2026
Video Highlights the 4 Key Steps to Successful Incident Response Dec 02, 2019
Helping Non-Security Stakeholders Understand ATT&CK in 10 Minutes or Less [VI
Crowdstrike
May 2021 Patch Tuesday: Updates and Analysis
blogs_crowdstrike·CVSS 7.5
CVE-2026-20929 [HIGH] May 2021 Patch Tuesday: Updates and Analysis
How CrowdStrike is Accelerating Exposure Evaluation as Adversaries Gain Speed Apr 06, 2026
STARDUST CHOLLIMA Likely Compromises Axios npm Package Apr 01, 2026
Falcon for IT Supports Windows Secure Boot Certificate Lifecycle Management Apr 01, 2026
Detecting CVE-2026-20929: Kerberos Authentication Relay via CNAME Abuse Mar 31, 2026
How CrowdStrike is Accelerating Exposure Evaluation as Adversaries Gain Speed Apr 06, 2026
STARDUST CHOLLIMA Likely Compromises Axios npm Package Apr 01, 2026
Falcon for IT Supports Windows Secure Boot Certificate Lifecycle Management Apr 01, 2026
Detecting CVE-2026-20929: Kerberos Authentication Relay via CNAME Abuse Mar 31, 2026
Video Highlights the 4 Key Steps to Successful Incident Response Dec 02, 2019
Helping Non-Security Stakeholders Understand AT
http://packetstormsecurity.com/files/163497/Microsoft-Hyper-V-vmswitch.sys-Proof-Of-Concept.htmlhttps://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-28476http://packetstormsecurity.com/files/163497/Microsoft-Hyper-V-vmswitch.sys-Proof-Of-Concept.htmlhttps://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-28476
2021-05-11
Published