CVE-2026-106563: Input Validation Flaw (CVSS 5.3)

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.

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CVSS v3.1 Score

5.3

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

Weakness Type (CWE)

CWE-20 Improper Input Validation

CWE-862 Missing Authorization

References

Other References

https://github.com/backstage/backstage/commit/2d5d3e77d630455d6d48cfa8f31fd3c126fd6f29 https://github.com/backstage/backstage/releases/tag/v1.54.1 https://github.com/backstage/backstage/security/advisories/GHSA-r9ph-3637-55px

Frequently Asked Questions

What is CVE-2026-106563? +

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. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-106563? +

CVE-2026-106563 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2026-106563? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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