CVE-2026-39961 Aiven Operator has cross-namespace secret exfiltration via ClickhouseUser connInfoSecretSource
A developer can exfiltrate secrets from other namespaces by exploiting a confused deputy flaw in the Aiven Operator's ClickhouseUser handling.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-39961?
CVE-2026-39961 is a medium-severity vulnerability in aiven-operator, published on 9 Apr 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
Aiven Operator allows you to provision and manage Aiven Services from your Kubernetes cluster. From 0.31.0 to before 0.37.0, a developer with create permission on ClickhouseUser CRDs in their own namespace can exfiltrate secrets from any other namespace — production database credentials, API keys, service tokens — with a single kubectl apply. The operator reads the victim's secret using its ClusterRole and writes the password into a new secret in the attacker's namespace. The operator acts as a confused deputy: its ServiceAccount has cluster-wide secret read/write (aiven-operator-role ClusterRole), and it trusts user-supplied namespace values in spec.connInfoSecretSource.namespace without validation. No admission webhook enforces this boundary — the ServiceUser webhook returns nil, and no ClickhouseUser webhook exists. This vulnerability is fixed in 0.37.0.
Which versions are affected by CVE-2026-39961?
3 open source packages ship an affected version, including github.com/aiven/aiven-operator. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/aiven/aiven-operator Go | From 0.31.0 | 0.37.0 |
github.com/aiven/aiven-operator Go | From 0.31.0 | 0.37.0 |
github.com/aiven/aiven-operator Go | From 0.31.0 | 0.37.0 |
Products include Aiven Aiven Operator.
How do I fix CVE-2026-39961?
Upgrade github.com/aiven/aiven-operator to 0.37.0 or later.
Is CVE-2026-39961 being exploited?
There is no known exploitation of CVE-2026-39961 in the wild and no public exploit code.
Sources
Also known as GHSA-99j8-wv67-4c72, GO-2026-5283.