CERT-In Vulnerability Note
CIVN-2025-0133
Denial of Service Vulnerability in Cisco Meraki MX and Meraki Z Series Teleworker Gateway
Original Issue Date:June 20, 2025
Severity Rating: HIGH
Systems Affected
- Cisco Meraki products if they are running a vulnerable release of Cisco Meraki MX firmware and have Cisco AnyConnect VPN with client certificate authentication enabled:
- MX64 , MX64W, MX65 , MX65W , MX67 , MX67C , MX67W , MX68 , MX68CW , MX68W , MX75 , MX84 , MX85 , MX95, MX100 , MX105 , MX250 , MX400 , MX450 , MX600, vMX, Z3 , Z3C , Z4 , Z4C
Note: Cisco AnyConnect VPN is supported on Cisco Meraki MX and Cisco Meraki Z Series devices that run Cisco Meraki MX firmware releases 16.2 and later, except for Cisco Meraki MX64 and MX65, which support Cisco AnyConnect VPN only if they are running Cisco Meraki MX firmware releases 17.6 and later.
Overview
A vulnerability has been reported in Cisco AnyConnect VPN server of Cisco Meraki MX and Cisco Meraki Z Series Teleworker Gateway could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition in the Cisco AnyConnect service on an affected device.
Target Audience:
All IT administrators and individuals responsible for maintaining and updating Cisco Meraki MX and Cisco Meraki Z Series devices.
Risk Assessment:
High risk of data manipulation and service disruption.
Impact Assessment:
Potential impact on confidentiality, integrity, and availability of the system.
Description
This vulnerability exists due to variable initialization errors when an SSL VPN session is established. An attacker could exploit this vulnerability by sending a sequence of crafted HTTPS requests to an affected device.
Successful exploitation of this vulnerability could allow the attacker to Cisco AnyConnect VPN server to restart, resulting in the failure of all established SSL VPN sessions and forcing remote users to initiate a new VPN connection and re-authenticate.
Solution
Apply appropriate updates as mentioned in Cisco Advisory
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-meraki-mx-vpn-dos-sM5GCfm7
Vendor Information
CISCO
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-meraki-mx-vpn-dos-sM5GCfm7
References
CISCO
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-meraki-mx-vpn-dos-sM5GCfm7
CVE Name
CVE-2025-20271
Disclaimer
The information provided herein is on "as is" basis, without warranty of any kind.
Contact Information
Email: info@cert-in.org.in Phone: +91-11-22902657
Postal address
Indian Computer Emergency Response Team (CERT-In)
Ministry of Electronics and Information Technology
Government of India
Electronics Niketan
6, CGO Complex, Lodhi Road,
New Delhi - 110 003
India
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