Cisco Meraki MX/Meraki Z AnyConnect VPN Server double free

Summaryinfo

A vulnerability classified as critical has been found in Cisco Meraki MX and Meraki Z. Affected by this vulnerability is an unknown functionality of the component AnyConnect VPN Server. This manipulation causes double free. This vulnerability appears as CVE-2024-20498. The attack may be initiated remotely. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Cisco Meraki MX and Meraki Z (version now known) and classified as critical. Affected by this vulnerability is some unknown processing of the component AnyConnect VPN Server. The manipulation with an unknown input leads to a double free vulnerability. The CWE definition for the vulnerability is CWE-415. The product calls free() twice on the same memory address, potentially leading to modification of unexpected memory locations. As an impact it is known to affect availability. The summary by CVE is:

Multiple vulnerabilities in the Cisco AnyConnect VPN server of Cisco Meraki MX and Cisco Meraki Z Series Teleworker Gateway devices could allow an unauthenticated, remote attacker to cause a DoS condition in the AnyConnect service on an affected device. These vulnerabilities are due to insufficient validation of client-supplied parameters while establishing an SSL VPN session. An attacker could exploit these vulnerabilities by sending a crafted HTTPS request to the VPN server of an affected device. A successful exploit could allow the attacker to cause the Cisco AnyConnect VPN server to restart, resulting in the failure of the established SSL VPN connections and forcing remote users to initiate a new VPN connection and reauthenticate. A sustained attack could prevent new SSL VPN connections from being established. Note: When the attack traffic stops, the Cisco AnyConnect VPN server recovers gracefully without requiring manual intervention.

It is possible to read the advisory at sec.cloudapps.cisco.com. This vulnerability is known as CVE-2024-20498 since 11/08/2023. 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 07/03/2025).

The vulnerability scanner Nessus provides a plugin with the ID 241198 (Cisco Meraki 16.2 / 17 / 18.1 < 18.1.07.12 / 18.2 < 18.2.11.2 Multiple Vulnerabilities (cisco-sa-meraki-mx-vpn-dos-QTRHzG2)), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (241198). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

• Cisco

Name

• Meraki MX
• Meraki Z

License

• commercial

Website

• Vendor: https://www.cisco.com/

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Be aware that VulDB is the high quality source for vulnerability data.

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