Summary
Backstage has a sensitive information disclosure in Kubernetes resource queries
Workarounds
- Enable the permission framework and restrict
kubernetes.resources.readto trusted users. - Scope the RBAC of the service account used to reach each cluster so that it cannot read sensitive resource types. The recommended
ClusterRolein the Kubernetes plugin configuration documentation does not grant this access.
Impact
An authenticated user holding the standard Kubernetes resource read permission could retrieve sensitive values that the Kubernetes plugin is designed to mask, potentially exposing credentials and other confidential material held in the connected clusters. Exposure is limited to resources that the Backstage service account is permitted to read and that match the targeted catalog entity's namespace and label selector. Deployments whose cluster credentials do not grant read access to these resources are unaffected.
The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.
CVE-2026-106561 has a CVSS score of 5.0 (Medium). The vector is network-reachable, low 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 (0.21.9); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Fixed in @backstage/plugin-kubernetes-backend version 0.21.9
One behavior change is worth noting for adopters who expose custom resources: a custom resource whose list kind is reported by the API server as SecretList now has the values of its data field masked, matching how core Kubernetes Secrets have always been handled on other query paths.
Frequently Asked Questions
- What is CVE-2026-106561? CVE-2026-106561 is a medium-severity incorrect authorization vulnerability in @backstage/plugin-kubernetes-backend (npm), affecting versions < 0.21.9. It is fixed in 0.21.9. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
- How severe is CVE-2026-106561? CVE-2026-106561 has a CVSS score of 5.0 (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.
- Which versions of @backstage/plugin-kubernetes-backend are affected by CVE-2026-106561? @backstage/plugin-kubernetes-backend (npm) versions < 0.21.9 is affected.
- Is there a fix for CVE-2026-106561? Yes. CVE-2026-106561 is fixed in 0.21.9. Upgrade to this version or later.
- Is CVE-2026-106561 exploitable, and should I be worried? Whether CVE-2026-106561 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
- What actually determines whether CVE-2026-106561 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.
- How do I fix CVE-2026-106561? Upgrade
@backstage/plugin-kubernetes-backendto 0.21.9 or later.