CVE-2024-20513

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-10-02 · updated 2026-06-17
Weakness: CWE-639

Description

A vulnerability 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 for targeted users of the AnyConnect service on an affected device. This vulnerability is due to insufficient entropy for handlers that are used during SSL VPN session establishment. An unauthenticated attacker could exploit this vulnerability by brute forcing valid session handlers. An authenticated attacker could exploit this vulnerability by connecting to the AnyConnect VPN service of an affected device to retrieve a valid session handler and, based on that handler, predict further valid session handlers. The attacker would then send a crafted HTTPS request using the brute-forced or predicted session handler to the AnyConnect VPN server of the device. A successful exploit could allow the attacker to terminate targeted SSL VPN sessions, forcing remote users to initiate new VPN connections and reauthenticate.

Affected products

Cisco Meraki Mx100 Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx105 Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx250 Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx400 Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx450 Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx600 Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx64 Firmware: from 17.6.0 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx64W Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx65 Firmware: from 17.6.0 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx65W Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx67 Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx67C Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx67W Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx68 Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx68Cw Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx68W Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx75 Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx84 Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx85 Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Mx95 Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Vmx Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Z3 Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Z3C Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Z4 Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2
Cisco Meraki Z4C Firmware: from 16.2 before 18.211.2 — fixed in 18.211.2

How to fix

Upgrade to a fixed version: Cisco Meraki Mx100 Firmware 18.211.2; Cisco Meraki Mx105 Firmware 18.211.2; Cisco Meraki Mx250 Firmware 18.211.2; Cisco Meraki Mx400 Firmware 18.211.2; Cisco Meraki Mx450 Firmware 18.211.2; Cisco Meraki Mx600 Firmware 18.211.2; Cisco Meraki Mx64 Firmware 18.211.2; Cisco Meraki Mx64W Firmware 18.211.2; Cisco Meraki Mx65 Firmware 18.211.2; Cisco Meraki Mx65W Firmware 18.211.2; Cisco Meraki Mx67 Firmware 18.211.2; Cisco Meraki Mx67C Firmware 18.211.2. Check the vendor advisory for mitigations.

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-meraki-mx-vpn-dos-QTRHzG2

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