CVE-2021-34431 Denial of service in Eclipse Mosquitto

Medium 6.5 Published 22 Jul 2021 Updated 4 Aug 2024

An authenticated attacker can cause a memory leak in Eclipse Mosquitto via a crafted MQTT v5 CONNECT message, leading to denial of service.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2021-34431?

CVE-2021-34431 is a medium-severity denial of service vulnerability in The Eclipse Foundation Eclipse Mosquitto, published on 22 Jul 2021. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

In Eclipse Mosquitto version 1.6 to 2.0.10, if an authenticated client that had connected with MQTT v5 sent a crafted CONNECT message to the broker a memory leak would occur, which could be used to provide a DoS attack against the broker.

Weakness: CWE-401

Which versions are affected by CVE-2021-34431?

It affects 1 product.

Products include Eclipse Mosquitto.

How do I fix CVE-2021-34431?

Upgrade to a fixed version.

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-2021-34431 being exploited?

There is no known exploitation of CVE-2021-34431 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2021-34431, GHSA-j546-3m5x-fx7p, UBUNTU-CVE-2021-34431.