Authenticated service interruption via undisclosed hypervisor flaw
Published Jul 14, 2021 · Updated Aug 10, 2026
Denial of service in Hyper-V in affected Microsoft Windows and Windows Server builds allows remote authenticated users to interrupt the host. Microsoft has not published the flawed Hyper-V locus or the operation it performs incorrectly on attacker-controlled input. Exploitation requires low privileges and high-complexity network interaction; the documented consequence is host availability loss.
Summary
What happened
Denial of service in Hyper-V in affected Microsoft Windows and Windows Server builds allows remote authenticated users to interrupt the host. Microsoft has not published the flawed Hyper-V locus or the operation it performs incorrectly on attacker-controlled input. Exploitation requires low privileges and high-complexity network interaction; the documented consequence is host availability loss.
The record
- CVE
- CVE-2021-33755
- Published
- Jul 14, 2021
- Updated
- Aug 10, 2026
- Vendor
- Microsoft
- Product
- Windows Server 2019
- Classifications
- T1499.004
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 14, 2021CVE publishedPublication date reported by the CVE source.
- Aug 10, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=10.0.17763.0 <10.0.17763.2061
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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