Cisco · Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)
CVE-2024-20353
Cisco ASA and FTD Denial of Service Vulnerability
What it is
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.
CISA: Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) contain an infinite loop vulnerability that can lead to remote denial of service condition.
What to do
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Deadline for US federal agencies: May 1, 2024
More exploited flaws from Cisco
| Added | Vulnerability | Product | Severity | Attack chance |
|---|---|---|---|---|
| Oct 24, 2024 | ASA and FTD Denial-of-Service | Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) | Medium 5.8 | 16% |
| 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.