Cisco ASA/Firepower Threat Defense Software Inactive-to-Active ACL interpretation conflict

Summaryinfo

A vulnerability identified as problematic has been detected in Cisco ASA and Firepower Threat Defense Software. The affected element is an unknown function of the component Inactive-to-Active ACL. Performing a manipulation results in interpretation conflict. This vulnerability was named CVE-2024-20293. The attack may be initiated remotely. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Cisco ASA and Firepower Threat Defense Software (affected version not known). This affects some unknown functionality of the component Inactive-to-Active ACL. The manipulation with an unknown input leads to a interpretation conflict vulnerability. CWE is classifying the issue as CWE-436. Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state. This is going to have an impact on integrity. The summary by CVE is:

A vulnerability in the activation of an access control list (ACL) on Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass the protection that is offered by a configured ACL on an affected device. This vulnerability is due to a logic error that occurs when an ACL changes from inactive to active in the running configuration of an affected device. An attacker could exploit this vulnerability by sending traffic through the affected device that should be denied by the configured ACL. The reverse condition is also true—traffic that should be permitted could be denied by the configured ACL. A successful exploit could allow the attacker to bypass configured ACL protections on the affected device, allowing the attacker to access trusted networks that the device might be protecting. Note: This vulnerability applies to both IPv4 and IPv6 traffic as well as dual-stack ACL configurations in which both IPv4 and IPv6 ACLs are configured on an interface.

The advisory is shared at sec.cloudapps.cisco.com. This vulnerability is uniquely identified as CVE-2024-20293 since 11/08/2023. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for 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 07/30/2025).

Upgrading eliminates this vulnerability.

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Productinfo

Type

• Firewall Software

Vendor

• Cisco

Name

• ASA
• Firepower Threat Defense Software

License

• commercial

Website

• Vendor: https://www.cisco.com/

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

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