CVE-2024-20353
Cisco ASA and FTD Denial of Service Vulnerability
Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)
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.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 24 April 2024. US federal agencies were required to remediate it by 1 May 2024.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 69.8%, which is higher than 99.4% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Frequently asked questions
Is CVE-2024-20353 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2024-20353.
What does CVE-2024-20353 affect?
CVE-2024-20353 affects Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD). 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.
How severe is CVE-2024-20353?
CVE-2024-20353 is rated HIGH with a CVSS base score of 8.6. EPSS puts the probability of exploitation in the next 30 days at 69.8%, higher than 99.4% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 1 May 2024.
How should organisations respond to CVE-2024-20353?
Apply the vendor patch for Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.