Cisco Meraki MX up to 19.1 AnyConnect VPN Server uninitialized variable

Summaryinfo

A vulnerability has been found in Cisco Meraki MX up to 19.1 and classified as critical. Affected by this vulnerability is an unknown functionality of the component AnyConnect VPN Server. This manipulation causes uninitialized variable. This vulnerability is handled as CVE-2025-20212. The attack can be initiated remotely. There is not any exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability has been found in Cisco Meraki MX up to 19.1 and classified as critical. Affected by this vulnerability is an unknown part of the component AnyConnect VPN Server. The manipulation with an unknown input leads to a uninitialized variable vulnerability. The CWE definition for the vulnerability is CWE-457. The code uses a variable that has not been initialized, leading to unpredictable or unintended results. As an impact it is known to affect availability. The summary by CVE is:

A vulnerability in the Cisco AnyConnect VPN server of Cisco Meraki MX and Cisco Meraki Z Series devices could allow an authenticated, remote attacker to cause a denial of service (DoS) condition in the Cisco AnyConnect service on an affected device. To exploit this vulnerability, the attacker must have valid VPN user credentials on the affected device. This vulnerability exists because a variable is not initialized when an SSL VPN session is established. An attacker could exploit this vulnerability by supplying crafted attributes while establishing an SSL VPN session with 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 sessions 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 without manual intervention.

The advisory is shared at sec.cloudapps.cisco.com. This vulnerability is known as CVE-2025-20212 since 10/10/2024. The exploitation appears to be easy. The attack can be launched remotely. Neither technical details nor an exploit are publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 241196 (Cisco Meraki 16.2 / 17 / 18.1 < 18.1.07.12 / 18.2 < 18.2.11.4 / 19.1 < 19.1.4 DoS (cisco-sa-meraki-mx-vpn-dos-vNRpDvfb)), 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 (241196). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Vendor

• Cisco

Name

• Meraki MX

Version

• 16.2
• 16.3
• 16.4
• 16.5
• 16.6
• 17.3
• 17.6
• 17.7
• 17.8
• 17.9
• 17.10
• 18.1
• 18.2
• 19.1

License

• commercial

Website

• Vendor: https://www.cisco.com/

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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