CVE-2026-81963 Microsoft Windows: login or permission bypass
In plain words: A door that should be locked is not: part of the system can be reached without a valid login or permission. The attacker gets in as a user or administrator without knowing a password.
Confirmed exploited by CISA on · US federal patch deadline Sep 22, 2026
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. This one is aimed at devices or apps of the kind people own.
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 Link Following Vulnerability
- Product
- Microsoft Windows
- CISA description
- Microsoft Windows Update Stack contains a link following vulnerability that allows a local attacker to escalate privileges locally up to SYSTEM.
- Type of flaw
- Login or permission bypass (CWE-59, CWE-284)
- Confirmed exploited
- Sep 8, 2026
- US federal patch deadline
- Sep 22, 2026
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Answering about CVE-2026-81963 ·
Questions about CVE-2026-81963
Is CVE-2026-81963 being exploited?
Yes. CISA added CVE-2026-81963 to its Known Exploited Vulnerabilities catalog on Sep 8, 2026, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2026-81963?
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-2026-81963?
Only if you use Microsoft Windows. This one is aimed at devices or apps of the kind people own.