Backstage Plugin Proxy Backend vulnerabilities

2 vulnerabilities

Known vulnerabilities in Backstage Plugin Proxy Backend, newest first, with CVSS severity, EPSS, KEV listings, ransomware use and the affected versions.

6.4CVE-2026-106491backstagebackstage+2
EPSS score
0.27%
Backstage is an open framework for building developer portals. Prior to 0.6.17, the @backstage/plugin-proxy-backend package is affected by improper input validation in proxy-backend. 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. This issue is fixed in version 0.6.17.4.8CVE-2026-106456backstagebackstage+2
EPSS score
0.24%
Backstage is an open framework for building developer portals. From 0.5.0 until 0.6.18, the @backstage/plugin-proxy-backend package is affected by inconsistent credential enforcement for overlapping proxy routes. 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. This issue is fixed in version 0.6.18.