CVE-2022-20933 Cisco Meraki MX and Z3 Teleworker Gateway VPN Denial of Service Vulnerability

High 8.6 Published 26 Oct 2022 Updated 1 Nov 2024

Unauthenticated remote attackers can crash the Cisco AnyConnect VPN server via malicious requests, causing service disruption and forcing user re-authentication.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2022-20933?

CVE-2022-20933 is a high-severity denial of service vulnerability in Cisco Meraki MX Firmware, published on 26 Oct 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A vulnerability in the Cisco AnyConnect VPN server of Cisco Meraki MX and Cisco Meraki Z3 Teleworker Gateway devices could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient validation of client-supplied parameters while establishing an SSL VPN session. An attacker could exploit this vulnerability by crafting a malicious request and sending it to the affected device. A successful exploit could allow the attacker to cause the Cisco AnyConnect VPN server to crash and restart, resulting in the failure of the established SSL VPN connections and forcing remote users to initiate a new VPN connection and re-authenticate. 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. Cisco Meraki has released software updates that address this vulnerability.

Weakness: CWE-234

Which versions are affected by CVE-2022-20933?

It affects 23 products.

Products include Cisco Meraki Mx100 Firmware, Cisco Meraki Mx105 Firmware, Cisco Meraki Mx250 Firmware, Cisco Meraki Mx400 Firmware, Cisco Meraki Mx450 Firmware, Cisco Meraki Mx600 Firmware and 17 more.

How do I fix CVE-2022-20933?

No fix has been published for CVE-2022-20933 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2022-20933 being exploited?

There is no known exploitation of CVE-2022-20933 in the wild and no public exploit code.

Sources

Also known as GHSA-9vrx-xfr3-hfjj.