Cisco Secure Firewall Adaptive Security Appliance Software Rate Limiting resource consumption

Summaryinfo

A vulnerability, which was classified as critical, has been found in Cisco Secure Firewall Adaptive Security Appliance Software and Secure Firewall Threat Defense Software. This affects an unknown function of the component Rate Limiting. This manipulation causes resource consumption. This vulnerability appears as CVE-2026-20154. The attack may be initiated remotely. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Cisco Secure Firewall Adaptive Security Appliance Software and Secure Firewall Threat Defense Software (affected version unknown) and classified as critical. Affected by this vulnerability is an unknown functionality of the component Rate Limiting. The manipulation with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. As an impact it is known to affect availability. The summary by CVE is:

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. 

It is possible to read the advisory at sec.cloudapps.cisco.com. This vulnerability is known as CVE-2026-20154 since 10/08/2025. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/16/2026). The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading eliminates this vulnerability.

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Productinfo

Type

• Firewall Software

Vendor

• Cisco

Name

• Secure Firewall Adaptive Security Appliance Software
• Secure Firewall Threat Defense Software

License

• commercial

Website

• Vendor: https://www.cisco.com/

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