Infinite loop in Cisco Secure Firewall Threat Defense (FTD) and Cisco Secure Firewall Adaptive Security Appliance (ASA) - CVE-2026-20154

Vulnerability identifier: #VU150872

CSH Severity: Medium

CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-20154

CWE-ID: CWE-835

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to improper rate limiting for syslog message 419002. A remote attacker can consume all available system resources and cause denial of service conditions.

Cisco Secure Firewall Threat Defense (FTD)
Cisco Secure Firewall Adaptive Security Appliance (ASA)

Install updates from vendor's website.

Cisco Secure Firewall Threat Defense (FTD) - addressed in versions 7.0.9, 7.0.10, 7.2.11, 7.2.12, 7.4.7, 7.4.8, 7.6.6, 7.7.13, 9.16.4.89, 9.16.4.92, 9.16.4.103, 9.18.4.71, 9.18.4.76, 9.18.4.82, 9.18.4.94, 9.20.4.19, 9.20.4.22, 9.20.4.28, 9.20.4.30, 9.20.4.34, 9.20.4.49, 9.22.2.32, 9.22.3, 9.22.3.5, 9.22.3.26, 9.23.1.26, 9.23.1.32, 9.23.1.47, 9.24.1, 9.24.1.5, 9.24.1.9, 9.24.1.11, 9.24.1.26, 10.0.0, 10.0.2
Cisco Secure Firewall Adaptive Security Appliance (ASA) - addressed in versions 7.0.9, 7.0.10, 7.2.11, 7.2.12, 7.4.7, 7.4.8, 7.6.6, 7.7.13, 9.16.4.89, 9.16.4.92, 9.16.4.103, 9.18.4.71, 9.18.4.76, 9.18.4.82, 9.18.4.94, 9.20.4.19, 9.20.4.22, 9.20.4.28, 9.20.4.30, 9.20.4.34, 9.20.4.49, 9.22.2.32, 9.22.3, 9.22.3.5, 9.22.3.26, 9.23.1.26, 9.23.1.32, 9.23.1.47, 9.24.1, 9.24.1.5, 9.24.1.9, 9.24.1.11, 9.24.1.26, 10.0.0, 10.0.2

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ftd-logging-dos-ZXXNesfN

• Multiple vulnerabilities in Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense