CVE-2021-43890 Microsoft Windows: software flaw
In plain words: A mistake in the software that attackers have found a way to abuse. Depends on the product — see the description and the vendor advisory.
Confirmed exploited by CISA on · US federal patch deadline Dec 29, 2021
What to do
- Install Microsoft's security update for Windows. If no update exists, follow the vendor's workaround or stop using the product until one ships.
- Turn on automatic updates for the operating system and for Office, PDF and archive apps.
- Be careful with unexpected attachments — documents, .zip/.rar files and shortcuts are common bait.
- Use a normal (non-admin) account day to day and keep built-in protection like Microsoft Defender on.
Who is affected
Could reach you. Used in ransomware, which spreads to ordinary people and small businesses.
What's at risk: Your files, saved passwords and accounts. Many of these let a program that is already running gain full administrator control.
The details
- Official name
- Microsoft Windows AppX Installer Spoofing Vulnerability
- Product
- Microsoft Windows
- CISA description
- Microsoft Windows AppX Installer contains a spoofing vulnerability which has a high impacts to confidentiality, integrity, and availability.
- Type of flaw
- Software flaw
- Confirmed exploited
- Dec 15, 2021 — known to be used in ransomware attacks
- US federal patch deadline
- Dec 29, 2021
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Answering about CVE-2021-43890 ·
Questions about CVE-2021-43890
Is CVE-2021-43890 being exploited?
Yes. CISA added CVE-2021-43890 to its Known Exploited Vulnerabilities catalog on Dec 15, 2021, which means there is reliable evidence of real-world attacks, including by ransomware groups.
How do I fix CVE-2021-43890?
Install Microsoft's security update for Windows. If no update exists, follow the vendor's workaround or stop using the product until one ships. Turn on automatic updates for the operating system and for Office, PDF and archive apps.
Am I affected by CVE-2021-43890?
Only if you use Microsoft Windows. Used in ransomware, which spreads to ordinary people and small businesses.