CVE-2026-106488: Backstage Improper Authentication Vulnerability

HIGH
Advisory Identifier: GHSA-826h-28h9-65hg
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CVSS 8.1
CWE-287
Published
Advisory Summary

CVE-2026-106488 is a HIGH (CVSS 8.1) improper authentication vulnerability (CWE-287: Improper Authentication) affecting Backstage libraries in the npm ecosystem. The issue involves improper authentication in the oidc provider. Remediation is available by upgrading affected packages to version 0.4.20.

CVE-2026-106488 at a Glance

CVE Identifier CVE-2026-106488
GHSA Identifier GHSA-826h-28h9-65hg
Severity HIGH
CVSS v3.1 Base Score 8.1
CWE Classification CWE-287: Improper Authentication
Affected Product Backstage
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 8.1

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2026-106488

To remediate this vulnerability, upgrade all affected Backstage dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

@backstage/plugin-auth-backend-module-oidc-provider fixed: 0.4.20 
npm install @backstage/plugin-auth-backend-module-oidc-provider@0.4.20
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls @backstage/plugin-auth-backend-module-oidc-provider

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-106488, inspect your project dependencies using npm:

npm ls @backstage/plugin-auth-backend-module-oidc-provider

Analyze the terminal output to locate any version of Backstage in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.4.20), your application is affected.

Note: The npm ls @backstage/plugin-auth-backend-module-oidc-provider 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-287: Improper Authentication, where when an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. In Backstage, 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

### Impact Deployments using OIDC email-based identity resolution with a provider that permits unverified email addresses may allow an authenticated provider user to assume another catalog identity. This may grant access and permissions associated with that user. No direct availability impact is demonstrated. ### Patches Patched in `@backstage/plugin-auth-backend-module-oidc-provider` version `0.4.20`. ### Workarounds - Disable email-based sign-in resolution for the OIDC provider, or require the identity provider to verify email addresses before allowing sign-in.

CVE-2026-106488 Affected Backstage Versions

1 component(s)
Fixed Versions:
0.4.20
Product / Package Ecosystem Affected Versions Fixed Version
@backstage/plugin-auth-backend-module-oidc-provider
npm/@backstage/plugin-auth-backend-module-oidc-provider
npm
< 0.4.20
0.4.20

References

GitHub Advisory / Wiki ADVISORY
https://github.com/backstage/backstage/security/advisories/GHSA-826h-28h9-65hg
NVD — CVE-2026-106488 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-106488
Security Fix Commit FIX COMMIT
https://github.com/backstage/backstage/commit/1b1f05e82161aaabc226c1d7d498d746956bf942
Backstage Source Repository REPOSITORY
https://github.com/backstage/backstage
Backstage Release RELEASE
https://github.com/backstage/backstage/releases/tag/v1.54.6

Frequently Asked Questions

What is CVE-2026-106488?
CVE-2026-106488 is a security vulnerability in Backstage involving Improper authentication in the OIDC provider under CWE-287: Improper Authentication.
Which Backstage versions are affected?
Affected versions include releases prior to 0.4.20 across affected packages: @backstage/plugin-auth-backend-module-oidc-provider.
What version fixes CVE-2026-106488?
Upgrading to 0.4.20 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @backstage/plugin-auth-backend-module-oidc-provider affected?
Yes, @backstage/plugin-auth-backend-module-oidc-provider is affected in releases prior to 0.4.20. Upgrade your dependency to 0.4.20 or later.
What is the CVSS score of CVE-2026-106488?
CVE-2026-106488 has a CVSS v3.1 base score of 8.1 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-106488?
CVE-2026-106488 is classified under CWE-287: Improper Authentication (When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.).
How can I check npm dependencies for CVE-2026-106488?
Run the dependency tree command: 'npm ls @backstage/plugin-auth-backend-module-oidc-provider'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-826h-28h9-65hg",
  "modified" : "2026-10-07T18:01:02Z",
  "published" : "2026-10-07T18:01:02Z",
  "aliases" : [ "CVE-2026-106488" ],
  "summary" : "Backstage: Improper authentication in the OIDC provider",
  "details" : "### Impact\n\nDeployments using OIDC email-based identity resolution with a provider that permits unverified email addresses may allow an authenticated provider user to assume another catalog identity. This may grant access and permissions associated with that user. No direct availability impact is demonstrated.\n\n### Patches\n\nPatched in `@backstage/plugin-auth-backend-module-oidc-provider` version `0.4.20`.\n\n### Workarounds\n\n- Disable email-based sign-in resolution for the OIDC provider, or require the identity provider to verify email addresses before allowing sign-in.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@backstage/plugin-auth-backend-module-oidc-provider"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.4.20"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/backstage/backstage/security/advisories/GHSA-826h-28h9-65hg"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-106488"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/backstage/backstage/commit/1b1f05e82161aaabc226c1d7d498d746956bf942"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/backstage/backstage"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/backstage/backstage/releases/tag/v1.54.6"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-287" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-07T18:01:02Z",
    "nvd_published_at" : "2026-10-06T21:17:17Z"
  }
}