CVE-2026-66793
Description
A flaw was found in the governance-policy-addon-controller component of Red Hat Advanced Cluster Management for Kubernetes. A user with permissions to annotate the namespaced ManagedClusterAddOn resource can override the governance-policy container image. This allows an attacker to run a controlled image with cluster-admin privileges on the managed cluster, leading to arbitrary code execution and privilege escalation.
Statement
This Critical vulnerability in Red Hat Advanced Cluster Management for Kubernetes enables remote code execution on managed clusters. An attacker with namespace-level annotate permissions on the hub can override the governance-policy container image via ManagedClusterAddOn annotations. This allows the execution of arbitrary code with cluster-admin privileges on the spoke cluster, bypassing image security controls.
Mitigation
To mitigate this issue, restrict users' ability to annotate ManagedClusterAddOn resources within the hub cluster. Ensure that only trusted administrators have namespace-level annotate permissions on these resources. Regularly review and audit permissions related to ManagedClusterAddOn resources to prevent unauthorized modifications. If a service is restarted or reloaded, these permission changes will persist.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.8 | N/A | 8.8 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Red Hat CVSS v3 Score Explanation
AV:N — Kubernetes API server. AC:L — single annotation on ManagedClusterAddOn resource. PR:L — namespace-level annotate permission on hub. UI:N — no user interaction. S:U — vulnerability is in the addon-controller's value override logic; treating its own security context as the boundary. C:H/I:H/A:H — attacker-controlled container runs with cluster-admin on managed cluster.
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
An attacker could provide unexpected values and cause a program crash or arbitrary control of resource allocation, leading to excessive consumption of resources such as memory and CPU.
Confidentiality
Technical Impact: Read Memory; Read Files or Directories
An attacker could read confidential data if they are able to control resource references.
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
An attacker could use malicious input to modify data or possibly alter control flow in unexpected ways, including arbitrary command execution.
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