CVE-2025-21391 Microsoft Windows: file path flaw
In plain words: The program can be tricked into reading or writing files outside the folder it should stay in. Leaks files such as passwords and settings, or overwrites important ones.
Confirmed exploited by CISA on · US federal patch deadline Mar 4, 2025
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 Storage Link Following Vulnerability
- Product
- Microsoft Windows
- CISA description
- Microsoft Windows Storage contains a link following vulnerability that could allow for privilege escalation. This vulnerability could allow an attacker to delete data including data that results in the service being unavailable.
- Type of flaw
- File path flaw (CWE-59)
- Confirmed exploited
- Feb 11, 2025
- US federal patch deadline
- Mar 4, 2025
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Answering about CVE-2025-21391 ·
Questions about CVE-2025-21391
Is CVE-2025-21391 being exploited?
Yes. CISA added CVE-2025-21391 to its Known Exploited Vulnerabilities catalog on Feb 11, 2025, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2025-21391?
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-2025-21391?
Only if you use Microsoft Windows. This one is aimed at devices or apps of the kind people own.