CVE-2026-106489: Backstage: Improper authorization enforcement for TechDocs static content

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-06 · updated 2026-10-22
Weakness: CWE-22

Description

Backstage is an open framework for building developer portals. Prior to 2.2.4, the @backstage/plugin-techdocs-backend package is affected by improper authorization enforcement for techdocs static content. An authenticated user with access to one TechDocs documentation site could craft a URL able to read documentation belonging to a different entity. This only affects deployments using the external TechDocs builder with an external storage provider (S3, GCS, etc.) and the permission framework enabled. Instances that do not use the permission framework are unaffected, since TechDocs content is visible to all authenticated users by design. This issue is fixed in version 2.2.4.

Affected products

backstage: before 1.54.6 — fixed in 1.54.6
Linuxfoundation Backstage/Plugin-Techdocs-Backend: before 2.2.4 — fixed in 2.2.4

How to fix

Upgrade to a fixed version: backstage 1.54.6; Linuxfoundation Backstage/Plugin-Techdocs-Backend 2.2.4. Check the vendor advisory for mitigations.

References

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