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

> An unauthenticated attacker can join the Juju Dqlite database cluster due to missing certificate validation, gaining full read and write access to the data.

- **Severity:** Critical 10.0 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Apr 2026
- **Updated:** 8 Apr 2026
- **Also known as:** GHSA-gvrj-cjch-728p, GO-2026-5405

## What is CVE-2026-4370?

CVE-2026-4370 is a critical authentication bypass vulnerability in Canonical Juju, published on 1 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-306 (Missing Authentication for Critical Functionality), CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2026-4370?

3 open source packages ship an affected version, including github.com/juju/juju. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/juju/juju` | Go | All versions | None |
| `github.com/juju/juju` | Go | All versions to 0.0.0-20260401092550-1c1ac1922b57 | None |
| `github.com/juju/juju` | Go | All versions to 0.0.0-20260401092550-1c1ac1922b57 | None |

Products: Canonical Juju.

## How do I fix CVE-2026-4370?

Upgrade to a fixed version.

## Is CVE-2026-4370 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-4370 exists.

## Other vulnerabilities in Canonical Juju

- [CVE-2026-5412](https://insights.sbomify.com/CVE-2026-5412/): Juju CloudSpec API could leak senstive information (critical 9.9)
- [CVE-2017-9232](https://insights.sbomify.com/CVE-2017-9232/): Juju uses a UNIX domain socket without setting appropriate permissions (critical 9.8)
- [CVE-2026-32693](https://insights.sbomify.com/CVE-2026-32693/): Unauthorized access to Kubernetes secrets in Juju (high 8.8)
- [CVE-2025-0928](https://insights.sbomify.com/CVE-2025-0928/): Arbitrary executable upload via authenticated endpoint (high 8.8)
- [CVE-2025-53513](https://insights.sbomify.com/CVE-2025-53513/): Zip slip vulnerability in Juju (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4370 and fix it if it is affected.

What it is: CVE-2026-4370 is a critical authentication bypass vulnerability in Canonical Juju, published on 1 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-4370 exists.

Affected packages and fixed versions:
- github.com/juju/juju (Go): affected all versions; no fix listed
- github.com/juju/juju (Go): affected all versions up to 0.0.0-20260401092550-1c1ac1922b57; no fix listed
- github.com/juju/juju (Go): affected all versions up to 0.0.0-20260401092550-1c1ac1922b57; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-4370/ (Markdown: https://insights.sbomify.com/CVE-2026-4370/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4370
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4370
- OSV: https://osv.dev/vulnerability/CVE-2026-4370

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-4370/
Summaries are generated and may contain mistakes; the official description above is the record.