CVE-2026-39961

Credits

Credits to Andrés Cruciani for finding and reporting the bug through our bug bounty program

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.

The application assigns, modifies, tracks, or checks privileges incorrectly, allowing a user to gain elevated access. Typical impact: privilege escalation beyond the intended level.

CVE-2026-39961 has a CVSS score of 6.8 (Medium). The vector is network-reachable, high privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.37.0); upgrading removes the vulnerable code path.

Kodem intelligence

This vulnerability is resolved in version 0.37.0. We recommend all users update as soon as possible.

1. What is CVE-2026-39961? CVE-2026-39961 is a medium-severity improper privilege management vulnerability in github.com/aiven/aiven-operator (go), affecting versions >= 0.31.0, < 0.37.0. It is fixed in 0.37.0. The application assigns, modifies, tracks, or checks privileges incorrectly, allowing a user to gain elevated access.
2. How severe is CVE-2026-39961? CVE-2026-39961 has a CVSS score of 6.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/aiven/aiven-operator are affected by CVE-2026-39961? github.com/aiven/aiven-operator (go) versions >= 0.31.0, < 0.37.0 is affected.
4. Is there a fix for CVE-2026-39961? Yes. CVE-2026-39961 is fixed in 0.37.0. Upgrade to this version or later.
5. Is CVE-2026-39961 exploitable, and should I be worried? Whether CVE-2026-39961 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-39961 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-39961? Upgrade github.com/aiven/aiven-operator to 0.37.0 or later.