Windows AppX Installer Spoofing Vulnerability

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

• CISA KEV Listed since 15 Dec 2021: known to be exploited. CISA reports use in ransomware campaigns.
• EPSS 0.11, the 96th percentile, on 10 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 15 Dec 2021. New records show when each source confirmed them.

Sources

• CVE List: CVE-2021-43890
• NVD: CVE-2021-43890

References from the CNA

• portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43890
• www.bleepingcomputer.com/news/microsoft/microsoft-disables-msix-protocol-handler-abused-in-malware-attacks/
• thehackernews.com/2023/12/microsoft-disables-msix-app-installer.html
• www.microsoft.com/en-us/security/blog/2023/12/28/financially-motivated-threat-actors-misusing-app-installer/
• github.com/ChrisTitusTech/winutil/pull/26

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.