CVE-2024-20499 Denial of service in Cisco Meraki MX Firmware

High 8.6 Published Updated

Unauthenticated remote attackers can cause a denial of service in the Cisco AnyConnect VPN server by sending crafted HTTPS requests, disrupting established connections.

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-2024-20499?

CVE-2024-20499 is a high-severity denial of service vulnerability in Cisco Meraki MX Firmware, published on 2 Oct 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Multiple vulnerabilities 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 in the AnyConnect service on an affected device.

These vulnerabilities are due to insufficient validation of client-supplied parameters while establishing an SSL VPN session. An attacker could exploit these vulnerabilities by sending a crafted HTTPS request to the VPN server of 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 connections 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 gracefully without requiring manual intervention.

Weakness: CWE-787

Which versions are affected by CVE-2024-20499?

It affects 25 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 19 more.

How do I fix CVE-2024-20499?

No fix has been published for CVE-2024-20499 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-2024-20499 being exploited?

There is no known exploitation of CVE-2024-20499 in the wild and no public exploit code.

Sources

Also known as GHSA-2287-j5fq-5mhv.

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