Microsoft Windows
YES - ON THE CISA KEV LIST
CVE-2021-43890
Microsoft Windows AppX Installer Spoofing Vulnerability
overdue since 2021-12-29
Microsoft: 391 entries (22.0% of all KEV entries are from this vendor); 41 added in 2026.
BOD 26-04 note: this is the date printed in the CISA catalog. A federal agency's actual deadline is set by its SSVC tier - Act (3 days), Attend (14 days), Track (60 days), or the next scheduled upgrade - counted from the KEV listing date or the date the vulnerability is identified in its environment, whichever comes first. Use the tier helper on each CVE page for your own window.
Your BOD 26-04 window (SSVC tier helper)
Your remediation window ends:
Description
Microsoft Windows AppX Installer contains a spoofing vulnerability which has a high impacts to confidentiality, integrity, and availability.
Required action (CISA)
Apply updates per vendor instructions.
Notes
https://nvd.nist.gov/vuln/detail/CVE-2021-43890
References
Other KEV entries for this vendor: Microsoft
- CVE-2026-124194 - Office (2026-11-10)
- CVE-2026-96951 - Windows (2026-10-13)
- CVE-2026-65660 - SharePoint (2026-09-25)
- CVE-2026-81963 - Windows (2026-09-08)
- CVE-2026-85880 - Windows (2026-09-08)
- CVE-2019-1068 - SQL Server (2026-08-26)
- CVE-2026-33824 - Internet Key Exchange (IKE) Service Extensions (2026-08-18)
- CVE-2026-55040 - SharePoint (2026-08-18)
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