Disclosure summary
### Impact An operator can configure overlapping proxy paths with different credential requirements. When a parent path permits unauthenticated access and a nested path requires credentials, the parent exemption can also cover requests handled by the nested proxy. An unauthenticated caller may therefore reach the nested upstream through Backstage, including with static upstream credentials configured for that proxy. Exploitation requires this specific overlapping route configuration. The resulting confidentiality and integrity impact depends on the capabilities exposed by the nested upstream. ### Patches Upgrade `@backstage/plugin-proxy-backend` to version `0.6.18` or later. The fixed package is available in [Backstage v1.55.0](https://github.com/backstage/backstage/releases/tag/v1.55.0). ### Workarounds - Avoid nesting a credential-protected proxy path below a path configured with `dangerously-allow-unauthenticated`. - Apply the same credential requirement to overlapping proxy paths. - Restrict direct network access to the Backstage backend until the patched package is deployed.
Source-specific records & product guidance
Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.
GitHub Reviewed Security Advisories · GHSA-472h-9c5j-prrr
Open original source · Updated Oct 07, 2026
Backstage: Inconsistent credential enforcement for overlapping proxy routes
Source severity: MEDIUM / 0
| Ecosystem | Package | Affected range | First patched |
|---|---|---|---|
| npm | @backstage/plugin-proxy-backend | >= 0.5.0, < 0.6.18 | 0.6.18 |
Original records & references
- NIST NVD record
- CVE Program record
- github.com — Reviewed advisory
PUBLISHED 2026-10-07T16:25:13-04:00
MODIFIED 2026-10-07T16:25:13-04:00
INGESTED 2026-10-08T12:30:39-04:00