CVE-2025-20393 Cisco Multiple Products: 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 24, 2025
What to do
- Install Cisco's security update for Multiple Products. If no update exists, follow the vendor's workaround or stop using the product until one ships.
- Patch edge devices first — attackers often start scanning for them within hours of a fix.
- Never expose the device's admin page to the internet.
- After patching a device that was exposed, follow the vendor's compromise checks, end active sessions and change passwords.
Who is affected
Work IT. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.
What's at risk: They face the internet and guard the whole network, so a flaw here can hand attackers a way in — and these devices usually run no antivirus, so break-ins go unnoticed.
The details
- Official name
- Cisco Multiple Products Improper Input Validation Vulnerability
- Product
- Cisco Multiple Products
- CISA description
- Cisco Secure Email Gateway, Secure Email, AsyncOS Software, and Web Manager appliances contains an improper input validation vulnerability that allows threat actors to execute arbitrary commands with root privileges on the underlying operating system of an affected appliance.
- Type of flaw
- Software flaw (CWE-20)
- Confirmed exploited
- Dec 17, 2025
- US federal patch deadline
- Dec 24, 2025
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Answering about CVE-2025-20393 ·
Questions about CVE-2025-20393
Is CVE-2025-20393 being exploited?
Yes. CISA added CVE-2025-20393 to its Known Exploited Vulnerabilities catalog on Dec 17, 2025, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2025-20393?
Install Cisco's security update for Multiple Products. If no update exists, follow the vendor's workaround or stop using the product until one ships. Patch edge devices first — attackers often start scanning for them within hours of a fix.
Am I affected by CVE-2025-20393?
Only if you use Cisco Multiple Products. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.