# 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.

- **Severity:** Medium 6.8 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Apr 2026
- **Updated:** 10 Apr 2026
- **Also known as:** GHSA-99j8-wv67-4c72, GO-2026-5283

## 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.

Weakness: CWE-441 (Unintended Proxy or Intermediary), CWE-269 (Improper Privilege Management)

## 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 | Ecosystem | 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: 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-39961 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-39961 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/aiven/aiven-operator (Go): affected from 0.31.0; fixed in 0.37.0
- github.com/aiven/aiven-operator (Go): affected from 0.31.0; fixed in 0.37.0
- github.com/aiven/aiven-operator (Go): affected from 0.31.0; fixed in 0.37.0

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-2026-39961/ (Markdown: https://insights.sbomify.com/CVE-2026-39961/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-39961
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39961
- OSV: https://osv.dev/vulnerability/CVE-2026-39961

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-39961/
Summaries are generated and may contain mistakes; the official description above is the record.