Backstage: Improper input validation in proxy-backend
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.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | @backstage/plugin-proxy-backend | < 0.6.17 | 0.6.17 |
References
- 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
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N- Weakness (CWE)
CWE-20, CWE-22- Platform
- npm
- Package
@backstage/plugin-proxy-backend- Disclosed
- 07.10.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-9ghw-48h5-v2w5 - CC BY 4.0
Vulnerability history: @backstage/plugin-proxy-backend
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 10.2026 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 2
Disclosures per year
- 2026: 2
-
Backstage: Improper input validation in proxy-backend this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.