CVE-2026-106563: backstage Improper Input Validation

Vulnerability summary

CVE-2026-106563 is a medium (CVSS 6.5) Improper Input Validation vulnerability in backstage. EPSS estimates a 0.22% chance of exploitation in the next 30 days, higher than 12.3% of scored vulnerabilities.

Timeline

1. 07-10-2026
   PublishedVulnerability first disclosed.
2. 10-10-2026
   Last modifiedVulnerability information updated.

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.

• CWE-20Improper Input ValidationThe product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
• CWE-862Missing AuthorizationThe product does not perform an authorization check when an actor attempts to access a resource or perform an action.