Back
CVE-2021-1691
Windows Hyper-V Denial of Service Vulnerability
High7.7EPSS 4.1%
- Published
- Updated
- Reserved
- Assigned by
- microsoft
Description
Windows Hyper-V Denial of Service Vulnerability
Timeline
ID reserved
By microsoft
- 41 days later
· 41 days later
Published
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| microsoftCNA (assigner) | 3.1 | High7.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C |
| NVDNVD · Modified | 3.1 | High7.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 4.1% · top 9.3% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.7.
Weakness
- Denial of Service
Affected products
Microsoft · Windows Server version 20H2
- affected 10.0.0 – < publication
Microsoft · Windows 10 Version 1909
- affected 10.0.0 – < publication
Microsoft · Windows Server, version 1909 (Server Core installation)
- affected 10.0.0 – < publication
Microsoft · Windows 10 Version 2004
- affected 10.0.0 – < publication
Microsoft · Windows Server version 2004
- affected 10.0.0 – < publication
References (2)
- Windows Hyper-V Denial of Service Vulnerability (opens in a new tab)vendor-advisory
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1691 (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2021-1691)Record last updated .