Vulnerability in @Backstage Plugin-Scaffolder-Backend
CVE-2026-106503
Backstage is an open framework for building developer portals. Prior to 3.3.1, 3.4.1, 4.0.3 and 4.1.0, the @backstage/plugin-scaffolder-backend package is affected by scaffolder action input authorization bypass. An authenticated user with access to affected Scaffolder templates could bypass configured action restrictions. Depending on integration credentials, this could grant unauthorized access to repositories and related source-control resources. This issue is fixed in versions 3.3.1, 3.4.1, 4.0.3 and 4.1.0.
Published · last modified .
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
- @Backstage Plugin-Scaffolder-Backend — versions < 3.3.1, >= 3.4.0, < 3.4.1, >= 4.0.0, < 4.0.3
- Backstage — versions < 1.49.6, >= 1.50.0-next.0, < 1.50.5, >= 1.51.0-next.0, < 1.54.6
Weakness classification (CWE)
References
- github.com/backstage/backstage/security/advisories/GHSA-hmp2-4m7g-22cv
- github.com/backstage/backstage/commit/11c1384c0649b8ab26391c6a4e4f34b80ab0d188
- github.com/backstage/backstage/commit/a91ed72d540e80b62a73b39bb1563ff5018d52d1
- github.com/backstage/backstage/commit/e307e4f487103d815e484291b3fda778ab9983bf
- github.com/backstage/backstage/releases/tag/v1.49.6
- github.com/backstage/backstage/releases/tag/v1.50.5
- github.com/backstage/backstage/releases/tag/v1.54.6
Frequently asked questions
- What is CVE-2026-106503?
- CVE-2026-106503 is a high-severity vulnerability in @Backstage Plugin-Scaffolder-Backend, classified under Improper Handling of Case Sensitivity. CVSS score: 8.1/10. Published 2026-10-06.
- How severe is CVE-2026-106503?
- High severity. CVSS v3 base score is 8.1 out of 10.