On 2024-04-24, CISA added CVE-2024-20353 (Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)) to its Known Exploited Vulnerabilities (KEV) catalog [2]. The vulnerability is listed in the catalog as "Cisco ASA and FTD Denial of Service Vulnerability" [2]. CISA requires remediation in accordance with the listed vendor mitigation guidance; see the original text in the body for specific requirements [2].
Backfill: this event became public on Apr 24, 2024 and we added it on Nov 10, 2026. It is not a new event.
CISA Adds Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) Vulnerability CVE-2024-20353 to Known Exploited Vulnerabilities Catalog
1 min read
- Disclosed
- Apr 24, 2024
- Published
- Nov 10, 2026
- Last updated
- Nov 8, 2026
- CVSS basis
- Our assessment
- 69.8%, higher than 99% of CVEs
- Exploitation and patch status
- ExploitedKEV
- Attack vector
- Vulnerability status
- Actor type
- Motivation
On this page
30-second summary
What happened
Who is affected
Industries mainly affected: Government, Cross-industry
What to do nowOur advice
CISA requires remediation in accordance with the listed vendor mitigation guidance; see the original text in the body for specific requirements [2].
Timeline
Technical details
CISA KEV Listing Record
CISA added CVE-2024-20353 (Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)) to the Known Exploited Vulnerabilities () catalog on 2024-04-24 [2].
Original Technical 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. [2]
Official Required Action
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. [2]
Individual Vulnerability Record
The U.S. National Vulnerability Database (NVD) provides an independent vulnerability record and description for CVE-2024-20353 [1].
References
Official / primary3
- [1]
“A vulnerability in the management and VPN web servers for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. ”
- [2]
This site aggregates public information and is not security consulting advice. Test remediation steps before applying.