Cisco Secure Firewall Adaptive Security Appliance Software Access Control List access control

Summaryinfo

A vulnerability classified as critical has been found in Cisco Secure Firewall Adaptive Security Appliance Software and Secure Firewall Threat Defense Software. Affected is an unknown function of the component Access Control List Handler. The manipulation leads to access control. This vulnerability is traded as CVE-2026-20073. It is possible to initiate the attack remotely. There is no exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Cisco Secure Firewall Adaptive Security Appliance Software and Secure Firewall Threat Defense Software (version now known) and classified as critical. This issue affects some unknown processing of the component Access Control List Handler. The manipulation with an unknown input leads to a access control vulnerability. Using CWE to declare the problem leads to CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

A vulnerability in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to send traffic that should be denied through an affected device. This vulnerability is due to improper error handling when an affected device that is joining a cluster runs out of memory while replicating access control rules. An attacker could exploit this vulnerability by sending traffic that should be blocked through the device. A successful exploit could allow the attacker to bypass access controls and reach devices in protected networks.

The advisory is shared at sec.cloudapps.cisco.com. The identification of this vulnerability is CVE-2026-20073 since 10/08/2025. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 05/05/2026). MITRE ATT&CK project uses the attack technique T1068 for this issue.

Upgrading eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion