CVE-2021-1691

HIGHNVD 7.77.7—

7.7

Windows Hyper-V Denial of Service Vulnerability

CVSS v3: 7.7
EG Score: 7.7(medium)
EPSS: 75.8%
KEV: Not listed

Published

January 12, 2021

Last Modified

November 21, 2024

References (2)

secure@microsofthttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1691
af854a3a-2127-422b-91ae-364da2661108https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1691

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Microsoft MSRCCVE-2021-16912021-01-12
Windows Hyper-V Denial of Service Vulnerability

Data Freshness Timeline

(refreshed 13× in last 7d / 20× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

2026-06-08 14:15 UTCEPSS rescore
2026-06-08 14:15 UTCEPSS rescore
2026-06-07 15:23 UTCEPSS rescore
2026-06-07 15:23 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-05 22:45 UTCEPSS rescore
2026-06-05 22:45 UTCEPSS rescore
2026-06-05 06:09 UTCEPSS rescore
2026-06-05 06:09 UTCEPSS rescore
2026-06-05 06:08 UTCEPSS rescore
2026-06-04 13:10 UTCEPSS rescore
2026-06-02 20:11 UTCEPSS rescore
2026-06-02 20:11 UTCEPSS rescore
2026-06-01 13:50 UTCEPSS rescore
2026-06-01 13:50 UTCEPSS rescore
2026-05-31 22:29 UTCEPSS rescore
2026-05-31 22:29 UTCEPSS rescore
2026-05-31 00:15 UTCEPSS rescore

Frequently asked(5)

What is CVE-2021-1691?

CVE-2021-1691 is a high vulnerability published on January 12, 2021. Windows Hyper-V Denial of Service Vulnerability

When was CVE-2021-1691 disclosed?

CVE-2021-1691 was first published in the National Vulnerability Database on January 12, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-1691 actively exploited?

CVE-2021-1691 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 75.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-1691?

CVE-2021-1691 has a CVSS v3 base score of 7.7 (NVD).

How do I remediate CVE-2021-1691?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-1691, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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CVE-2021-1691

📅 Published

🔄 Last Modified

🔗 References (2)