CVE-2026-32236: @backstage/plugin-auth-backend SSRF Vulnerability
LOWCVE-2026-32236 is a LOW ssrf vulnerability (CWE-918: Server-Side Request Forgery (SSRF)) affecting @backstage/plugin-auth-backend libraries in the npm ecosystem. The issue involves ssrf in experimental cimd metadata fetch. Remediation is available by upgrading affected packages to version 0.27.1.
CVE-2026-32236 at a Glance
How to Fix CVE-2026-32236
To remediate this vulnerability, upgrade all affected @backstage/plugin-auth-backend dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
npm install @backstage/plugin-auth-backend@0.27.1Run the following command in your project directory to verify that all resolved dependencies use the patched release:
npm ls @backstage/plugin-auth-backendHow to Check if You Are Affected
To determine whether your Node.js application is affected by CVE-2026-32236, inspect your project dependencies using npm:
npm ls @backstage/plugin-auth-backendAnalyze the terminal output to locate any version of @backstage/plugin-auth-backend in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.27.1), your application is affected.
Note: The npm ls @backstage/plugin-auth-backend command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-918: Server-Side Request Forgery (SSRF), where the web server receives a url or similar request from an upstream component and retrieves the contents of this url, but it does not sufficiently ensure that the request is being sent to the expected destination. In @backstage/plugin-auth-backend, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-32236 Affected @backstage/plugin-auth-backend Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
@backstage/plugin-auth-backend
|
npm |
< 0.27.1
|
0.27.1
|
References
Frequently Asked Questions
What is CVE-2026-32236?
Which @backstage/plugin-auth-backend versions are affected?
What version fixes CVE-2026-32236?
Is @backstage/plugin-auth-backend affected?
What CWE is associated with CVE-2026-32236?
How can I check npm dependencies for CVE-2026-32236?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-qp4c-xg64-7c6x",
"modified" : "2026-04-15T20:46:59Z",
"published" : "2026-03-12T14:51:02Z",
"aliases" : [ "CVE-2026-32236" ],
"summary" : "@backstage/plugin-auth-backend: SSRF in experimental CIMD metadata fetch",
"details" : "### Impact \n \n A Server-Side Request Forgery (SSRF) vulnerability exists in `@backstage/plugin-auth-backend` when `auth.experimentalClientIdMetadataDocuments.enabled` is set to `true`. The CIMD \n metadata fetch validates the initial `client_id` hostname against private IP ranges but does not apply the same validation after HTTP redirects.\n \n 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\n enabled via an experimental flag that is off by default. Deployments that restrict `allowedClientIdPatterns` to specific trusted domains are not affected.\n\n ### Patches\n\n Patched in `@backstage/plugin-auth-backend` version `0.27.1`. The fix disables HTTP redirect following when fetching CIMD metadata documents.\n\n ### Workarounds\n\n Disable the experimental CIMD feature by removing or setting `auth.experimentalClientIdMetadataDocuments.enabled` to `false` in your app-config. This is the default configuration.\n Alternatively, restrict `allowedClientIdPatterns` to specific trusted domains rather than using the default wildcard pattern.\n\n ### References\n\n - [IETF Client ID Metadata Document draft](https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/)\n - [MCP Authorization Specification - Client ID Metadata Documents](https://modelcontextprotocol.io/specification/2025-11-25/basic/authorization#client-id-metadata-documents)",
"severity" : [ {
"type" : "CVSS_V4",
"score" : "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"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "npm",
"name" : "@backstage/plugin-auth-backend"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "0.27.1"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/security/advisories/GHSA-qp4c-xg64-7c6x"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-32236"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/commit/17038abf2dfdb4abc08a59b1c95af39851de0e07"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/backstage/backstage"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-918" ],
"severity" : "LOW",
"github_reviewed" : true,
"github_reviewed_at" : "2026-03-12T14:51:02Z",
"nvd_published_at" : "2026-03-12T19:16:18Z"
}
}