CVE-2026-4370: Juju has Improper TLS Client/Server authentication and certificate verification on Database Cluster

Any Juju controller since 3.2.0.

An attacker with only route-ability to the target juju controller Dqlite cluster endpoint may join the Dqlite cluster, read and modify all information, including escalating privileges, open firewall ports etc.

This is due to not checking the client certificate, additionally, the client does not check the server’s certificate (MITM attack possible), so anything goes.

https://github.com/juju/juju/blob/001318f51ac456602aef20b123684f1eeeae9a77/internal/database/node.go#L312-L324