Cisco IOS up to 15.2(8)E6 on Catalyst access control

Summaryinfo

A vulnerability was found in Cisco IOS on Catalyst. It has been classified as critical. The affected element is an unknown function. The manipulation leads to access control. This vulnerability is uniquely identified as CVE-2025-20137. The attack can only be initiated within the local network. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Cisco IOS on Catalyst. It has been rated as critical. This issue affects an unknown code block. 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 the access control list (ACL) programming of Cisco IOS Software that is running on Cisco Catalyst 1000 Switches and Cisco Catalyst 2960L Switches could allow an unauthenticated, remote attacker to bypass a configured ACL. This vulnerability is due to the use of both an IPv4 ACL and a dynamic ACL of IP Source Guard on the same interface, which is an unsupported configuration. An attacker could exploit this vulnerability by attempting to send traffic through an affected device. A successful exploit could allow the attacker to bypass an ACL on the affected device. Note: Cisco documentation has been updated to reflect that this is an unsupported configuration. However, Cisco is publishing this advisory because the device will not prevent an administrator from configuring both features on the same interface. There are no plans to implement the ability to configure both features on the same interface on Cisco Catalyst 1000 or Catalyst 2960L Switches.

It is possible to read the advisory at sec.cloudapps.cisco.com. The identification of this vulnerability is CVE-2025-20137 since 10/10/2024. The exploitation is known to be easy. Access to the local network is required for this attack. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 08/05/2025). The attack technique deployed by this issue is T1068 according to MITRE ATT&CK.

Upgrading eliminates this vulnerability.

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Productinfo

Type

• Router Operating System

Vendor

• Cisco

Name

• IOS

Version

• 15.2(5a)E
• 15.2(5b)E
• 15.2(5c)E
• 15.2(6)E
• 15.2(6)E0c
• 15.2(6)E1
• 15.2(6)E2
• 15.2(6)E2b
• 15.2(6)E3
• 15.2(7)E
• 15.2(7)E0a
• 15.2(7)E0s
• 15.2(7)E1
• 15.2(7)E1a
• 15.2(7)E2
• 15.2(7)E3
• 15.2(7)E3k
• 15.2(7)E4
• 15.2(7)E5
• 15.2(7)E6
• 15.2(7)E7
• 15.2(7)E8
• 15.2(7)E9
• 15.2(7)E10
• 15.2(7)E11
• 15.2(7)E12
• 15.2(7a)E0b
• 15.2(7b)E0b
• 15.2(8)E
• 15.2(8)E1
• 15.2(8)E2
• 15.2(8)E3
• 15.2(8)E4
• 15.2(8)E5
• 15.2(8)E6

License

• commercial

Website

• Vendor: https://www.cisco.com/

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