CVE-2026-78609: Incorrect Authorization (CWE-863) in Elastic Cloud on Kubernetes (ECK) can lead to unauthorized modification o

Routine

MEDIUM 5.4WATCHLISTUPGRADE

CVE-2026-78609 is a medium-severity flaw (CVSS 5.4) affecting elastic cloud on kubernetes. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Incorrect Authorization (CWE-863) in Elastic Cloud on Kubernetes (ECK) can lead to unauthorized modification of data via Metadata Spoofing (CAPEC-690). An actor holding limited Kubernetes permissions confined to a single namespace could cause attacker-controlled certificate material to be included in the Elasticsearch client trust bundle managed by ECK in a separate namespace.

Why this priority

On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.1% (top 96%)
CISA exploited list	No
Weakness	CWE-863
Published	2026-09-02
Last modified	2026-09-04

Publisher (CNA): Elastic · Vendor: elastic

Last updated 2026-09-04 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-02 15:17 UTCPublished CVE record published
2026-09-04 16:39 UTCUpdated Record last modified

elastic elastic cloud on kubernetes UPGRADE

Affected: >= 2.6.0 and < 3.5.0

Fixed in: 3.5.0

Safe to downgrade to: a release before 2.6.0

1. Check installed version

apt-cache policy elastic-cloud-on-kubernetes || rpm -q elastic-cloud-on-kubernetes || elastic-cloud-on-kubernetes --version

2. UPGRADE to 3.5.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade elastic-cloud-on-kubernetes

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade elastic-cloud-on-kubernetes

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.6.0 (Debian / Ubuntu)

apt-cache madison elastic-cloud-on-kubernetes sudo apt install elastic-cloud-on-kubernetes=<VERSION_BEFORE_2.6.0> sudo apt-mark hold elastic-cloud-on-kubernetes

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list elastic-cloud-on-kubernetes sudo dnf downgrade elastic-cloud-on-kubernetes-<VERSION_BEFORE_2.6.0> sudo dnf versionlock add elastic-cloud-on-kubernetes

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-78609?

elastic cloud on kubernetes: upgrade to 3.5.0. Exact commands for each OS are on this page.

Is CVE-2026-78609 being exploited?

CVE-2026-78609 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-78609 affect?

CVE-2026-78609 affects elastic cloud on kubernetes. Severity is medium (CVSS 5.4). Incorrect Authorization (CWE-863) in Elastic Cloud on Kubernetes (ECK) can lead to unauthorized modification of data via Metadata Spoofing (CAPEC-690). An actor holding limited Kubernetes permissions confined to a single namespace could cau

How urgent is CVE-2026-78609?

Priority 25/100. On your watchlist

Software pages

Kubernetes vulnerabilities · Elasticsearch vulnerabilities

Related CVEs

CVE-2026-72648 MEDIUM 6.5 UPGRADE Cleartext Storage of Sensitive Information in an Environment Variable (CWE-526) in Elastic Cloud on Kubernetes
CVE-2026-78600 LOW 3.5 UPGRADE Incomplete Cleanup (CWE-459) in Elastic Cloud on Kubernetes (ECK) can lead to unauthorized access via Privileg
CVE-2026-72640 MEDIUM 6.5 UPGRADE The Elastic Cloud on Kubernetes (ECK) operator reads a list of secret references from an annotation on secrets

References

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