What is the CVSS score of CVE-2026-39961?

CVE-2026-39961 has a CVSS 3.1 base score of 6.8 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N. EPSS exploitation probability: 0.0%.

Is there a patch available for CVE-2026-39961?

Yes, a patch is available for CVE-2026-39961. Update the affected software to the latest version immediately.

Kubernetes CVE-2026-39961

EUVD-2026-20965 MEDIUM

Improper Privilege Management (CWE-269)

2026-04-09 GitHub_M

GHSA-99j8-wv67-4c72

Kubernetes Privilege Escalation

6.8

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

6.8 MEDIUM

AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

None

Availability

None

Lifecycle Timeline

Patch released

Apr 10, 2026 - 20:30 nvd

Patch available

EUVD ID Assigned

Apr 09, 2026 - 17:45 euvd

EUVD-2026-20965

Analysis Generated

Apr 09, 2026 - 17:45 vuln.today

CVE Published

Apr 09, 2026 - 17:14 nvd

MEDIUM 6.8

DescriptionGitHub Advisory

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.

AnalysisAI

Aiven Operator versions 0.31.0 through 0.36.x allow developers with ClickhouseUser CRD creation permissions in their own namespace to exfiltrate secrets from arbitrary namespaces by exploiting a confused deputy vulnerability in the operator's ClusterRole. An attacker can craft a malicious ClickhouseUser resource that causes the operator to read privileged credentials (database passwords, API keys, service tokens) from production namespaces and write them into the attacker's namespace with a single kubectl apply command. The vulnerability is fixed in version 0.37.0.

Technical ContextAI

Aiven Operator is a Kubernetes controller that provisions and manages Aiven cloud services through custom resource definitions (CRDs). The vulnerability stems from insufficient validation in the spec.connInfoSecretSource.namespace field of the ClickhouseUser CRD. The operator's ServiceAccount is granted a broad ClusterRole (aiven-operator-role) with cluster-wide secret read and write permissions, following least-privilege failure patterns. When processing ClickhouseUser resources, the operator trusts user-supplied namespace values without validation, allowing an attacker to reference secrets in other namespaces. This is a classic confused deputy problem (CWE-269: Improper Access Control): the operator, trusted to read secrets in its own scope, is manipulated into accessing resources outside intended boundaries because no admission webhook (neither the ServiceUser webhook nor a ClickhouseUser-specific webhook) enforces namespace isolation at the API server level. The operator reads the victim namespace's secret using its elevated permissions and writes the extracted credentials into a new secret in the attacker's namespace.

RemediationAI

Vendor-released patch: upgrade Aiven Operator to version 0.37.0 or later. This release includes the fix that validates namespace values in spec.connInfoSecretSource.namespace and implements proper admission controls to prevent cross-namespace secret access. Users should deploy the patched version immediately to all Kubernetes clusters running affected versions. Additionally, as an interim mitigation until upgrade is possible, restrict RBAC permissions for ClickhouseUser CRD creation to trusted personnel only and audit existing ClickhouseUser resources for potentially malicious namespace references in spec.connInfoSecretSource. See the GitHub security advisory at https://github.com/aiven/aiven-operator/security/advisories/GHSA-99j8-wv67-4c72 for additional details and the release notes at https://github.com/aiven/aiven-operator/releases/tag/v0.37.0 for upgrade instructions.