CVE-2019-14850

A denial of service vulnerability was discovered in nbdkit. An attacker could connect to the nbdkit service and cause it to perform a large amount of work in initializing backend plugins, by simply opening a connection to the service. This vulnerability could cause resource consumption and degradation of service in nbdkit, depending on the plugins configured on the server-side.

Mitigation

This attack is only possible if nbdkit is configured with a plugin that does a lot of work in its initial .open() callback. Some examples that do a lot of work are nbdkit-ssh-plugin and nbdkit-guestfs-plugin. The nbdkit-memory-plugin is an example that does very little work, and thus is not subject to this vulnerability.

Only attackers that can connect to the nbdkit service can exploit this vulnerability. If nbdkit is not exposed over TCP (eg, nbdkit -U), or is bound only to a private network interface, or is protected by firewall rules, the attack surface is correspondingly limited.