CVE-2024-20353 Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD): 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 May 1, 2024
What to do
- Install Cisco's security update for Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD). 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 ASA and FTD Denial of Service Vulnerability
- Product
- Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)
- CISA description
- Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) contain an infinite loop vulnerability that can lead to remote denial of service condition.
- Type of flaw
- Software flaw (CWE-835)
- Confirmed exploited
- Apr 24, 2024
- US federal patch deadline
- May 1, 2024
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Answering about CVE-2024-20353 ·
Questions about CVE-2024-20353
Is CVE-2024-20353 being exploited?
Yes. CISA added CVE-2024-20353 to its Known Exploited Vulnerabilities catalog on Apr 24, 2024, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2024-20353?
Install Cisco's security update for Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD). 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-2024-20353?
Only if you use Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD). Aimed mostly at company systems — you are affected through the companies you use, not your own phone.