@backstage/plugin-auth-backend: SSRF in experimental CIMD metadata fetch

高 7.5CVE-2026-32236 · GHSA-qp4c-xg64-7c6x · 12/03/2026 公開 · 17/06/2026 更新

要点

CVE-2026-32236 は backstage (linuxfoundation), @backstage/plugin-auth-backend に影響する深刻度「高」 (CVSS 7.5) の脆弱性です。
今後30日間に悪用される確率（EPSS）：0.31%（全脆弱性の 24.0% より高い）。
対処：0.27.1 以降に更新してください。

パッケージ	影響を受けるバージョン	修正済みバージョン
backstage linuxfoundation	`≤ 0.27.0`	修正版なし
@backstage/plugin-auth-backend npm	`< 0.27.1`	`0.27.1`

概要

Impact

A Server-Side Request Forgery (SSRF) vulnerability exists in @backstage/plugin-auth-backend when auth.experimentalClientIdMetadataDocuments.enabled is set to true. The CIMD metadata fetch validates the initial client_id hostname against private IP ranges but does not apply the same validation after HTTP redirects.

The practical impact is limited. The attacker cannot read the response body from the internal request, cannot control request headers or method, and the feature must be explicitly enabled via an experimental flag that is off by default. Deployments that restrict allowedClientIdPatterns to specific trusted domains are not affected.

Patches

Patched in @backstage/plugin-auth-backend version 0.27.1. The fix disables HTTP redirect following when fetching CIMD metadata documents.

Workarounds

Disable the experimental CIMD feature by removing or setting auth.experimentalClientIdMetadataDocuments.enabled to false in your app-config. This is the default configuration. Alternatively, restrict allowedClientIdPatterns to specific trusted domains rather than using the default wildcard pattern.

References

NVD の説明

Backstage is an open framework for building developer portals. Prior to 0.27.1, a Server-Side Request Forgery (SSRF) vulnerability exists in @backstage/plugin-auth-backend when auth.experimentalClientIdMetadataDocuments.enabled is set to true. The CIMD metadata fetch validates the initial client_id hostname against private IP ranges but does not apply the same validation after HTTP redirects. The practical impact is limited. The attacker cannot read the response body from the internal request, cannot control request headers or method, and the feature must be explicitly enabled via an experimental flag that is off by default. Deployments that restrict allowedClientIdPatterns to specific trusted domains are not affected. Patched in @backstage/plugin-auth-backend version 0.27.1.