Backstage: Improper entity validation in deprecated Kubernetes services endpoint

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-106563: 0.22% estimated exploitation activity in the next 30 days; percentile 13.20 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact 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. Patches Patched in @backstage/plugin-kubernetes-backend version 0.21.8. Workarounds - Disable the deprecated /services/:serviceId route by deploying a custom Kubernetes router that omits it. - Restrict access to the kubernetes.resources.read permission to limit the set of users who can reach the endpoint.

Published by the source

7 Oct 2026, 18:02 UTC

Last modified by the source

7 Oct 2026, 18:15 UTC

Source last checked

26 Oct 2026, 13:07 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-r9ph-3637-55px

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-r9ph-3637-55px

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-r9ph-3637-55px

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# Patch Next advisory brief: CVE-2026-106563

Advisory: Backstage: Improper entity validation in deprecated Kubernetes services endpoint
IDs: CVE-2026-106563, GHSA-r9ph-3637-55px
Record: https://patchnext.com/advisories/cve-2026-106563 (revision 3, source checked 26 Oct 2026, 13:07 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @backstage/plugin-kubernetes-backend 0.21.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @backstage/plugin-kubernetes-backend: affected < 0.21.8; fixed in 0.21.8

## Suggested inspection (read-only)
- `npm ls @backstage/plugin-kubernetes-backend --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @backstage/plugin-kubernetes-backend.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-r9ph-3637-55px (GitHub-reviewed advisory GHSA-r9ph-3637-55px lists affected ranges: npm @backstage/plugin-kubernetes-backend >=0 <0.21.8)
- Verified: https://osv.dev/vulnerability/GHSA-r9ph-3637-55px (OSV record GHSA-r9ph-3637-55px lists affected ranges: npm @backstage/plugin-kubernetes-backend >=0 <0.21.8 (fixed))

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