Applied Cybernetics Group
Threat intel → detection pipeline
Friday, September 18, 2026
Data as of 13:09 UTC

Cisco ASA and FTD Denial of Service Vulnerability

Added to KEV
2024-04-24
Federal due date
2024-05-01
Vendor
Cisco
Product
Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)
EPSS
99.4th percentile (score 0.707, as of 2026-09-16)
NVD CVSS v3.1
8.6 (HIGH)
Ransomware use
Unknown
ATT&CK
T1037 , T1190 , T1608.001 , T1653 · signal rollup
Upstream
https://nvd.nist.gov/vuln/detail/CVE-2024-20353

CISA short 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.

Required action

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

NVD description

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. This vulnerability is due to incomplete error checking when parsing an HTTP header. An attacker could exploit this vulnerability by sending a crafted HTTP request to a targeted web server on a device. A successful exploit could allow the attacker to cause a DoS condition when the device reloads.

EPSS percentile is the FIRST.org exploit-probability ranking as of the date noted above; it moves daily. CVSS reflects NVD's analysis at time of publication.