CVE-2026-106498: @backstage Plugin-Catalog-Backend

High severity, CVSS 7.7. EPSS: 0.3% chance of exploitation in the next 30 days.

Backstage is an open framework for building developer portals. Prior to 3.5.1, 3.6.2, 3.7.2, 3.8.2 and 3.9.1, the @backstage/plugin-catalog-backend package is affected by improper url validation in catalog entity placeholder resolution. An authenticated Backstage user could craft a catalog entity with placeholder directives that reference resources outside the entity's source repository. Under certain configurations, this could allow access to data not intended to be available to the user. This issue is fixed in versions 3.5.1, 3.6.2, 3.7.2, 3.8.2 and 3.9.1.

Affected products

• @backstage Plugin-Catalog-Backend: before 3.5.1 (fixed in 3.5.1); from 3.6.0, before 3.6.2 (fixed in 3.6.2); from 3.7.0, before 3.7.2 (fixed in 3.7.2); from 3.8.0, before 3.8.2 (fixed in 3.8.2); from 3.9.0, before 3.9.1 (fixed in 3.9.1)
• Backstage Backstage: before 1.49.6 (fixed in 1.49.6); from 1.50.0-next.0, before 1.50.5 (fixed in 1.50.5); from 1.51.0-next.0, before 1.51.3 (fixed in 1.51.3); from 1.52.0-next.0, before 1.53.2 (fixed in 1.53.2); from 1.54.0-next.0, before 1.54.6 (fixed in 1.54.6)

Published 2026-10-06. Last modified 2026-10-09.