GHSA-472h-9c5j-prrr: Medium severity npm/@backstage/plugin-proxy-backend vulnerability
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.
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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
npm/@backstage/plugin-proxy-backendto a version that resolves this vulnerability.Fixed in 0.6.18 - Upgrade
Upgrade
@backstage/plugin-proxy-backendto a version that resolves this vulnerability.Fixed in 0.6.18 - Configuration
Apply the same credential requirement to overlapping proxy paths.
Backstage proxy paths credential requirements for overlapping paths = same credential requirement - Configuration
Avoid nesting a credential-protected proxy path below a path configured with dangerously-allow-unauthenticated.
Backstage proxy paths dangerously-allow-unauthenticated = do not use on a parent path of a credential-protected proxy path - Compensating control
Restrict direct network access to the Backstage backend until the patched package is deployed.