# CVE-2026-78609: Elastic Cloud on Kubernetes incorrect authorization in multi-tenant environments

Source: https://junglewise.ai/threats/cve-2026-78609-elastic-cloud-on-kubernetes-incorrect-authorization-in-multi  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-02. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-78609 · Severity: medium · CVSS 5.4 · Published 2026-09-02

Elastic Cloud on Kubernetes (ECK) is a Kubernetes operator that manages Elasticsearch deployments. In multi-tenant environments, an attacker with limited permissions in one Kubernetes namespace could inject malicious certificates into Elasticsearch's trust bundle used in a separate namespace, potentially allowing them to intercept or modify Elasticsearch client communications. This vulnerability only affects deployments where Elasticsearch client certificate authentication is in use.

Technologies: [Elastic Cloud on Kubernetes](https://junglewise.ai/threats/technologies/cloud-on-kubernetes). Vendors: [Elastic](https://junglewise.ai/threats/vendors/elastic).

## Quick answers

**Is CVE-2026-78609 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-78609 being exploited in the wild.

**How severe is CVE-2026-78609?** Medium severity, with a CVSS score of 5.4, published 2 September 2026.

**Which products and versions are affected?** Elastic Cloud on Kubernetes 2.6.0 through 3.4.1.

**Is there a fix for CVE-2026-78609?** A patch was published on 2026-09-01: Fixed in version 3.5.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-78609 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-78609?** Check whether you run Elastic Cloud on Kubernetes or Elastic Cloud On Kubernetes at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

This vulnerability is an incorrect authorization flaw (CWE-863) allowing metadata spoofing (CAPEC-690). An attacker with limited Kubernetes permissions confined to a single namespace can cause attacker-controlled certificate material to be included in the Elasticsearch client trust bundle managed by ECK in a separate namespace. The vulnerability requires network access and the attacker to already hold some Kubernetes permissions within their own namespace. By injecting rogue certificates, an attacker can potentially decrypt or forge Elasticsearch client communications. The issue is resolved in ECK version 3.5.0; all versions from 2.6.0 through 3.4.1 are affected. No workarounds are available.

## Affected products

- Elastic Cloud on Kubernetes 2.6.0 through 3.4.1

## Timeline

- 2026-09-01: disclosed
- 2026-09-01: patched: Fixed in version 3.5.0

## References

- [https://discuss.elastic.co/t/elastic-cloud-on-kubernetes-3-5-0-security-update-esa-2026-145/390105](https://discuss.elastic.co/t/elastic-cloud-on-kubernetes-3-5-0-security-update-esa-2026-145/390105)

## Related threats

- [Elastic Cloud on Kubernetes incomplete cleanup leading to unauthorized access](https://junglewise.ai/threats/cve-2026-78600-elastic-cloud-on-kubernetes-incomplete-cleanup-leading-to)
- [Elastic Cloud on Kubernetes cleartext storage of service account tokens](https://junglewise.ai/threats/cve-2026-72648-elastic-cloud-on-kubernetes-cleartext-storage-of-service-account)
- [Elastic Cloud on Kubernetes cross-namespace secret disclosure](https://junglewise.ai/threats/cve-2026-72640-elastic-cloud-on-kubernetes-cross-namespace-secret-disclosure)