CVE-2026-106504: @backstage Plugin-Scaffolder-Backend

Medium severity, CVSS 6.5. EPSS: 0.3% chance of exploitation in the next 30 days.

Backstage is an open framework for building developer portals. Prior to 4.1.0, the @backstage/plugin-scaffolder-backend package is affected by sensitive information exposure in scaffolder task logs. An authenticated user who can create and read scaffolder tasks may be able to observe sensitive values in task logs in deployments with restrictive action permissions and affected templates. Exploitation requires a denied action whose input contains such a value. This issue is fixed in version 4.1.0.

Affected products

• @backstage Plugin-Scaffolder-Backend: before 4.1.0 (fixed in 4.1.0)
• Backstage Backstage: before 1.54.6 (fixed in 1.54.6)

Published 2026-10-06. Last modified 2026-10-07.