CVE-2026-32236
highpriority · track · 30EPSS 0.003 · 23 %ileEUUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–high · 1.7–7.5
ssvc
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weaknesses
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affected products (3)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- GHSA-qp4c-xg64-7c6x@backstage/plugin-auth-backend: SSRF in experimental CIMD metadata fetch2026-03-12ghsa · osvUS
### 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)
also known as (3)
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sources
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references (8)
External citations — patches, advisories, analysis.
- https://access.redhat.com/security/cve/cve-2026-32236cnnvd
- https://github.com/backstage/backstage/commit/17038abf2dfdb4abc08a59b1c95af39851de0e07cnnvd
- https://github.com/backstage/backstage/releasesPatchcnnvd
- https://github.com/backstage/backstage/security/advisories/GHSA-qp4c-xg64-7c6xcnnvd
- https://github.com/backstage/backstage/commit/17038abf2dfdb4abc08a59b1c95af39851de0e07enisa_euvd
- https://github.com/backstage/backstage/security/advisories/GHSA-qp4c-xg64-7c6xenisa_euvd
- https://github.com/backstage/backstage/commit/17038abf2dfdb4abc08a59b1c95af39851de0e07Patchnvd
- https://github.com/backstage/backstage/security/advisories/GHSA-qp4c-xg64-7c6xVendor Advisorynvd
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