GHSA-472h-9c5j-prrr

Suggest an improvement
Source
https://github.com/advisories/GHSA-472h-9c5j-prrr
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-472h-9c5j-prrr/GHSA-472h-9c5j-prrr.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-472h-9c5j-prrr
Aliases
Published
2026-10-07T20:25:13Z
Modified
2026-10-07T20:30:07Z
Severity
  • 4.8 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N CVSS Calculator
Summary
Backstage: Inconsistent credential enforcement for overlapping proxy routes
Details

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.
Database specific 
{
    "cwe_ids": [
        "CWE-863"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-07T20:25:13Z",
    "nvd_published_at": "2026-10-06T21:17:15Z",
    "severity": "MODERATE"
}
References

Affected packages

npm / @backstage/plugin-proxy-backend

Package

Name
@backstage/plugin-proxy-backend
View open source insights on deps.dev
Purl
pkg:npm/%40backstage/plugin-proxy-backend

Affected ranges

Type
SEMVER
Events
Introduced
0.5.0
Fixed
0.6.18

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-472h-9c5j-prrr/GHSA-472h-9c5j-prrr.json"