Cisco · Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)
CVE-2024-20481
Cisco ASA and FTD Denial-of-Service Vulnerability
What it is
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.
CISA: Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) contain a missing release of resource after effective lifetime vulnerability that could allow an unauthenticated, remote attacker to cause a denial-of-service (DoS) of the RAVPN service.
What to do
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Deadline for US federal agencies: November 14, 2024
More exploited flaws from Cisco
| Added | Vulnerability | Product | Severity | Attack chance |
|---|---|---|---|---|
| Apr 24, 2024 | ASA and FTD Denial of Service | Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) | High 8.6 | 70% |
| Apr 24, 2024 | ASA and FTD Privilege Escalation | Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) | Medium 6.0 | 19% |
| Feb 15, 2024 | ASA and FTD Information Disclosure | Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) | High 7.5 | 72% |
| Nov 3, 2021 | ASA and FTD Read-Only Path Traversal | Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) | High 7.5 | >99.9% |
| Nov 3, 2021 | ASA and FTD Cross-Site Scripting (XSS) | Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) | Medium 6.1 | 86% |
| Oct 14, 2026 | Relative Path Traversal | Secure Email Gateway | Critical 9.8 | 2.2% |
| Sep 30, 2026 | Hex Encoding | Catalyst SD-WAN Manager | Critical 9.8 | 39% |
| Sep 16, 2026 | Incorrect Use of Privileged APIs | Identity Services Engine | Critical 10.0 | 76% |
Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.