CVE-2026-106488: @backstage Plugin-Auth-Backend-Module-Oidc-Provider

High severity, CVSS 8.1. EPSS: 0.3% chance of exploitation in the next 30 days.

Backstage is an open framework for building developer portals. Prior to 0.4.20, the @backstage/plugin-auth-backend-module-oidc-provider package is affected by improper authentication in the oidc provider. Deployments using OIDC email-based identity resolution with a provider that permits unverified email addresses may allow an authenticated provider user to assume another catalog identity. This may grant access and permissions associated with that user. No direct availability impact is demonstrated. This issue is fixed in version 0.4.20.

Affected products

• @backstage Plugin-Auth-Backend-Module-Oidc-Provider: before 0.4.20 (fixed in 0.4.20)
• Backstage Backstage: before 1.54.6 (fixed in 1.54.6)

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