CVE-2026-106563: Backstage: Improper entity validation in deprecated Kubernetes services endpoint

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-07 · updated 2026-10-16
Weakness: CWE-20

Description

Backstage is an open framework for building developer portals. Prior to 0.21.8, the @backstage/plugin-kubernetes-backend package is affected by improper entity validation in deprecated kubernetes services endpoint. An authenticated user with Kubernetes read permissions could access Kubernetes workload data beyond their intended scope by supplying crafted entity data to the deprecated services endpoint. The exposure is limited to read-only access to Kubernetes object metadata across configured clusters. This issue is fixed in version 0.21.8.

Affected products

backstage: before 1.54.1 — fixed in 1.54.1
Linuxfoundation Backstage/Plugin-Kubernetes-Backend: before 0.21.8 — fixed in 0.21.8

How to fix

Upgrade to a fixed version: backstage 1.54.1; Linuxfoundation Backstage/Plugin-Kubernetes-Backend 0.21.8. Check the vendor advisory for mitigations.

References

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