CVE-2021-1691

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

• ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
• AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

4.06% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 90.4% of scored records. A rank, not a probability.

NVD base score

7.7 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

NVD analysis status

Modified. NVD last modified this record on 2026-06-17.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2021-01-12 19:42Z5 YR AGO

Last updated

2024-11-19 15:20Z1 YR AGO

Reserved

2020-12-02

Assigning CNA

microsoft

Record state

PUBLISHED

Severity

High (CVSS 7.7)

CNA CVSS vector

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

Weaknesses

No CWE assigned

Data version

5.1

Document digest

98311712013016fa9a137c240e107d749bfa8a28855e11bfa1f95d7e0c0877dc

• msrc.microsoft.comWindows Hyper-V Denial of Service Vulnerabilityhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1691vendor-advisory
• portal.msrc.microsoft.comhttps://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1691x_refsource_MISC