CVE-2021-43890

Exploitation

Exploited in the wild. Listed in the CISA Known Exploited Vulnerabilities catalog on 2021-12-15. Federal remediation due 2021-12-29. Known ransomware campaign use: reported by CISA.

SSVC decision

• ExploitationactiveCISA reports credible evidence of active exploitation.
• AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
• Technical ImpacttotalSuccessful exploitation gives total 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

11.29% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 95.8% of scored records. A rank, not a probability.

NVD base score

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

NVD CVSS vector

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

NVD analysis status

Analyzed. NVD last modified this record on 2026-08-06.

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

2021-12-15 14:15Z4 YR AGO

Last updated

2026-08-06 03:55Z2 MO AGO

Reserved

2021-11-16

Assigning CNA

microsoft

Record state

PUBLISHED

Severity

High (CVSS 7.1)

CNA CVSS vector

CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Weaknesses

No CWE assigned

Data version

5.2

Document digest

f9eb02a9fcd8b71fb9e60c87abef0baf9f972fa635978c3a60a1640c003525cf

• portal.msrc.microsoft.comhttps://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43890x_refsource_MISC
• www.bleepingcomputer.comhttps://www.bleepingcomputer.com/news/microsoft/microsoft-disables-msix-protocol-handler-abused-in-malware-attacks/
• thehackernews.comhttps://thehackernews.com/2023/12/microsoft-disables-msix-app-installer.html
• www.microsoft.comhttps://www.microsoft.com/en-us/security/blog/2023/12/28/financially-motivated-threat-actors-misusing-app-installer/
• github.comhttps://github.com/ChrisTitusTech/winutil/pull/26
• www.cisa.govhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-43890government-resource