CVE-2026-106563: @backstage/plugin-kubernetes-backend - Improper Entity Validation in Deprecated Kubernetes Services Endpoint
Summary
CVE-2026-106563: Backstage: Improper entity validation in deprecated Kubernetes services endpoint. Affects @backstage/plugin-kubernetes-backend versions < 0.21.8. Fixed in 0.21.8. How to fix ↓
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Background
The @backstage/plugin-kubernetes-backend is a plugin for Backstage, a platform for building developer portals. This plugin enables users to interact with Kubernetes clusters, providing functionalities such as viewing workloads and managing services. However, it has a deprecated services endpoint that is vulnerable to improper entity validation, allowing unauthorized access to sensitive Kubernetes workload data.
Vulnerability Detail
The vulnerability arises from improper validation of entity data supplied to the deprecated services endpoint. An authenticated user with Kubernetes read permissions can exploit this flaw to access Kubernetes workload data beyond their intended scope. This exposure is limited to read-only access to Kubernetes object metadata across configured clusters, potentially leading to unauthorized information disclosure.
How To Fix
Minimum fixed version
0.21.8
This is the first release that contains the fix.
npm install @backstage/plugin-kubernetes-backend@0.21.8Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary measure, you can disable the deprecated '/services/:serviceId' route by deploying a custom Kubernetes router that omits this endpoint. Additionally, restrict access to the 'kubernetes.resources.read' permission to limit the set of users who can reach the endpoint.
Conclusion
In summary, the CVE-2026-106563 vulnerability in the @backstage/plugin-kubernetes-backend plugin allows authenticated users to access unauthorized Kubernetes workload data due to improper entity validation. It is crucial to update to the patched version or implement the suggested workarounds to mitigate the risk.
See every vulnerability recorded for @backstage/plugin-kubernetes-backend →
FAQ
The vulnerability is due to improper entity validation in the deprecated Kubernetes services endpoint, allowing unauthorized access to workload data.
Authenticated users with Kubernetes read permissions are affected, as they can exploit this vulnerability to access unauthorized data.
The main consequence is unauthorized read-only access to sensitive Kubernetes object metadata, which could lead to information disclosure.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
The CVSS score of this vulnerability is 5.3, indicating a moderate severity level.
References
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