CVE-2026-20154

High

Description

A vulnerability in the system rate-limiting process for syslog message 419002 of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause high CPU utilization on an affected device, resulting in a denial of service (DoS) condition. This vulnerability is due to improper rate limiting for syslog message 419002. An attacker could exploit this vulnerability by sending a flood of TCP synchronization (SYN) packets to an affected device. A successful exploit could allow the attacker to cause high CPU utilization, resulting in performance degradation. 

SeverityHigh
CVSS8.6
Exploit probability—
ProductCisco Secure Firewall Adaptive Security Appliance (ASA) Software
PublishedSep 16, 2026
First seenSep 16, 2026
Weakness typeCWE-835CWE-835

How to fix

Sources list no fixed version or patch link for this vulnerability.

Affected products

ProductAffected versionsFixed in
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software9.16.1, 9.16.1.28, 9.16.2, 9.16.2.3, 9.16.2.7, 9.16.2.11, 9.16.2.13, 9.16.2.14, 9.16.3.3, 9.16.3, 9.16.3.14, 9.18.1, 9.16.3.15, 9.18.1.3, 9.18.2, 9.16.3.19, 9.16.3.23, 9.18.2.5, 9.16.4, 9.18.2.7, 9.19.1, 9.16.4.9, 9.18.2.8, 9.16.4.14, 9.18.3, 9.19.1.5, 9.16.4.18, 9.19.1.9, 9.18.3.39, 9.16.4.19, 9.19.1.12, 9.18.3.46, 9.16.4.27, 9.19.1.18, 9.18.3.53, 9.18.3.55, 9.16.4.38, 9.16.4.39, 9.18.3.56, 9.20.1, 9.16.4.42, 9.19.1.22, 9.18.4, 9.20.1.5, 9.18.4.5, 9.19.1.24, 9.16.4.48, 9.18.4.8, 9.20.2, 9.19.1.27, 9.16.4.55, 9.18.4.22, 9.20.2.10, 9.16.4.57, 9.19.1.28, 9.18.4.24, 9.20.2.21, 9.16.4.61, 9.19.1.31, 9.18.4.29, 9.20.2.22, 9.16.4.62, 9.18.4.34, 9.20.3, 9.16.4.67, 9.16.4.70, 9.18.4.40, 9.23.1, 9.22.1.1, 9.16.4.71, 9.20.3.4, 9.18.4.47, 9.20.3.7, 9.19.1.37, 9.16.4.76, 9.20.3.9, 9.19.1.38, 9.18.4.50, 9.22.1.3, 9.20.3.10, 9.22.1.2, 9.18.4.52, 9.20.3.13, 9.22.1.6, 9.18.4.53, 9.16.4.82, 9.22.2, 9.20.3.16, 9.19.1.42, 9.18.4.57, 9.16.4.84, 9.23.1.3, 9.20.3.20, 9.22.2.4, 9.23.1.7, 9.20.4, 9.22.2.9, 9.23.1.13, 9.20.4.7, 9.22.2.13, 9.18.4.66, 9.20.4.10, 9.23.1.19, 9.16.4.85, 9.22.2.14, 9.18.4.67, 9.18.4.68, 9.23.1.22, 9.20.4.14, 9.22.2.20—
Cisco Cisco Secure Firewall Threat Defense (FTD) Software7.0.0, 7.0.0.1, 7.0.1, 7.0.1.1, 7.0.2, 7.2.0, 7.0.2.1, 7.0.3, 7.2.0.1, 7.0.4, 7.2.1, 7.0.5, 7.3.0, 7.2.2, 7.2.3, 7.3.1, 7.2.4, 7.0.6, 7.2.5, 7.2.4.1, 7.3.1.1, 7.4.0, 7.0.6.1, 7.2.5.1, 7.4.1, 7.2.6, 7.0.6.2, 7.4.1.1, 7.2.7, 7.2.5.2, 7.3.1.2, 7.2.8, 7.6.0, 7.4.2, 7.2.8.1, 7.0.6.3, 7.4.2.1, 7.2.9, 7.0.7, 7.7.0, 7.4.2.2, 7.2.10, 7.6.1, 7.4.2.3, 7.0.8, 7.6.2, 7.7.10, 7.7.11, 7.0.8.1, 7.6.2.1, 7.7.10.1, 7.4.2.4, 7.2.10.2, 7.4.3, 7.6.4, 7.4.4—

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CVE-2026-20154 · Cisco Secure Firewall Adaptive Security Appliance (ASA) Software · Dark Radar