CVE-2024-20481
Cisco ASA and FTD Denial-of-Service Vulnerability
Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)
A vulnerability in the Remote Access VPN (RAVPN) service of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) of the RAVPN service. This vulnerability is due to resource exhaustion. An attacker could exploit this vulnerability by sending a large number of VPN authentication requests to an affected device. A successful exploit could allow the attacker to exhaust resources, resulting in a DoS of the RAVPN service on the affected device. Depending on the impact of the attack, a reload of the device may be required to restore the RAVPN service. Services that are not related to VPN are not affected. Cisco Talos discussed these attacks in the blog post Large-scale brute-force activity targeting VPNs, SSH services with commonly used login credentials.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 24 October 2024. US federal agencies were required to remediate it by 14 November 2024.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 15.9%, which is higher than 96.9% 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:L
Frequently asked questions
Is CVE-2024-20481 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2024-20481.
What does CVE-2024-20481 affect?
CVE-2024-20481 affects Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD). A vulnerability in the Remote Access VPN (RAVPN) service of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) of the RAVPN service. This vulnerability is due to resource exhaustion. An attacker could exploit this vulnerability by sending a large number of VPN authentication requests to an affected device. A successful exploit could allow the attacker to exhaust resources, resulting in a DoS of the RAVPN service on the affected device. Depending on the impact of the attack, a reload of the device may be required to restore the RAVPN service. Services that are not related to VPN are not affected. Cisco Talos discussed these attacks in the blog post Large-scale brute-force activity targeting VPNs, SSH services with commonly used login credentials.
How severe is CVE-2024-20481?
CVE-2024-20481 is rated MEDIUM with a CVSS base score of 5.8. EPSS puts the probability of exploitation in the next 30 days at 15.9%, higher than 96.9% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 14 November 2024.
How should organisations respond to CVE-2024-20481?
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.