CVE-2026-32236
@backstage/plugin-auth-backend: SSRF in experimental CIMD metadata fetch
描述
### 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 - [IETF Client ID Metadata Document draft](https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/) - [MCP Authorization Specification - Client ID Metadata Documents](https://modelcontextprotocol.io/specification/2025-11-25/basic/authorization#client-id-metadata-documents)
如何修補 CVE-2026-32236
要修補 CVE-2026-32236,請將受影響套件升級到下列已修補版本。
- —升級至 0.27.1 或更新版本
CVE-2026-32236 正在被利用嗎?
低 — EPSS 為 0.3%,目前沒有觀察到大規模利用活動。