CVE-2026-4370: canonical juju Improper Certificate Validation

Vulnerability summary

CVE-2026-4370 is a critical (CVSS 10.0) Improper Certificate Validation vulnerability in canonical juju. EPSS estimates a 0.41% chance of exploitation in the next 30 days, higher than 34.1% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 01-04-2026
   PublishedVulnerability first disclosed.
2. 08-04-2026
   Last modifiedVulnerability information updated.

Description

A vulnerability was identified in Juju from version 3.2.0 until 3.6.19 and from version 4.0 until 4.0.4, where the internal Dqlite database cluster fails to perform proper TLS client and server authentication. Specifically, the Juju controller's database endpoint does not validate client certificates when a new node attempts to join the cluster. An unauthenticated attacker with network reachability to the Juju controller's Dqlite port can exploit this flaw to join the database cluster. Once joined, the attacker gains full read and write access to the underlying database, allowing for total data compromise.

• CWE-295Improper Certificate ValidationThe product does not validate, or incorrectly validates, a certificate.
• CWE-306Missing Authentication for Critical FunctionThe product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.