Auth bypass in @Backstage Plugin-Auth-Backend-Module-Oidc-Provider

CVE-2026-106488

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.

Vulnerability class: Broken Authentication

Published .

CVSS v3 metric

CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-106488?
CVE-2026-106488 is a high-severity vulnerability in @Backstage Plugin-Auth-Backend-Module-Oidc-Provider, classified under Improper Authentication. CVSS score: 8.1/10. Published 2026-10-06.
How severe is CVE-2026-106488?
High severity. CVSS v3 base score is 8.1 out of 10.