---
title: "CVE-2026-4370: Juju has Improper TLS Client/Server authentication and certificate verification on Database Cluster"
url: https://erroneo.us/security/cve/CVE-2026-4370/
description: "CVE-2026-4370 (github.com/juju/juju (Go)): 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…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-04-01
date_modified: 2026-04-08
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-4370"
kev: false
cvss: 10
epss: 0.00413
license: All rights reserved. Quote with attribution and a link.
---

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

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.4% , percentile 34: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 34% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes github.com/juju/juju (Go) <= 0.0.0-20260401092550-1c1ac1922b57, no fixed version listed . Check your lockfile, including transitive dependencies.

## What it is

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.

## Affected packages

- Go `github.com/juju/juju` <= 0.0.0-20260401092550-1c1ac1922b57 → fixed: none listed

## Affected products (CVE record)

- Canonical Juju: 3.2.0 < 3.6.20, 4.0 < 4.0.4

## Severity

- canonical CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`
- GitHub CVSS 3.1: 10.0 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.41% probability of exploitation activity in the next 30 days; percentile 34.

## Sources

- [GitHub Advisory GHSA-gvrj-cjch-728p](https://github.com/advisories/GHSA-gvrj-cjch-728p)
- [CVE.org record CVE-2026-4370](https://www.cve.org/CVERecord?id=CVE-2026-4370)
- [NVD entry CVE-2026-4370](https://nvd.nist.gov/vuln/detail/CVE-2026-4370)
- [github.com](https://github.com/juju/juju/security/advisories/GHSA-gvrj-cjch-728p)

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Source page: https://erroneo.us/security/cve/CVE-2026-4370/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt