GHSA-9ghw-48h5-v2w5
Backstage: Improper input validation in proxy-backend
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | @backstage/plugin-proxy-backend | < 0.6.17 | 0.6.17 |
Details
As written in the advisory (Markdown source, shown as plain text).
### Impact
An authenticated Backstage user could craft a request URL that causes the proxy-backend to forward the request to a path outside the configured base path on the target server. This is limited to target servers already configured as proxy endpoints and requires Backstage authentication by default.
### Patches
Patched in `@backstage/plugin-proxy-backend` version `0.6.17`
### Workarounds
- Deploy a reverse proxy or WAF in front of Backstage that normalizes request paths before they reach the backend.
References
External links from the advisory. They lead to third-party sites.
- https://github.com/backstage/backstage/security/advisories/GHSA-9ghw-48h5-v2w5
- https://nvd.nist.gov/vuln/detail/CVE-2026-106491
- https://github.com/backstage/backstage/commit/233287d0ce3133e41549bf92a7470c940a41753c
- https://github.com/backstage/backstage
- https://github.com/backstage/backstage/releases/tag/v1.54.6