CVE-2024-20509

Severity: medium (CVSS 5.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% 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-362

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 hijack an AnyConnect VPN session or cause a denial of service (DoS) condition for individual users of the AnyConnect VPN service on an affected device. This vulnerability is due to weak entropy for handlers that are used during the VPN authentication process as well as a race condition that exists in the same process. An attacker could exploit this vulnerability by correctly guessing an authentication handler and then sending crafted HTTPS requests to an affected device. A successful exploit could allow the attacker to take over the AnyConnect VPN session from a target user or prevent the target user from establishing an AnyConnect VPN session with the affected device.

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-by-QWUkqV7X

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