CVE-2026-106489: Backstage Remote Code Execution Vulnerability

MODERATE
Advisory Identifier: GHSA-rg9r-hr7g-5gc2
Share
CVSS 6.5
CWE-862 CWE-22
Published
Advisory Summary

CVE-2026-106489 is a MODERATE (CVSS 6.5) remote code execution vulnerability (CWE-862: Missing Authorization) affecting Backstage libraries in the npm ecosystem. The issue involves improper authorization enforcement for techdocs static content. Remediation is available by upgrading affected packages to version 2.2.4.

CVE-2026-106489 at a Glance

CVE Identifier CVE-2026-106489
GHSA Identifier GHSA-rg9r-hr7g-5gc2
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-862: Missing Authorization
Affected Product Backstage
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 6.5

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:N/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 None (I:N)
Availability None (A:N)

How to Fix CVE-2026-106489

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-techdocs-backend fixed: 2.2.4 
npm install @backstage/plugin-techdocs-backend@2.2.4
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-techdocs-backend

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-106489, inspect your project dependencies using npm:

npm ls @backstage/plugin-techdocs-backend

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 2.2.4), your application is affected.

Note: The npm ls @backstage/plugin-techdocs-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-862: Missing Authorization, where the product does not perform an authorization check when an actor attempts to access a resource or perform an action. 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 An authenticated user with access to one TechDocs documentation site could craft a URL able to read documentation belonging to a different entity. This only affects deployments using the external TechDocs builder with an external storage provider (S3, GCS, etc.) and the permission framework enabled. Instances that do not use the permission framework are unaffected, since TechDocs content is visible to all authenticated users by design. ### Patches Patched in `@backstage/plugin-techdocs-backend` version `2.2.4` ### Workarounds - None other than upgrading. Deployments that serve TechDocs from local storage are not affected.

CVE-2026-106489 Affected Backstage Versions

1 component(s)
Fixed Versions:
2.2.4
Product / Package Ecosystem Affected Versions Fixed Version
@backstage/plugin-techdocs-backend
npm/@backstage/plugin-techdocs-backend
npm
< 2.2.4
2.2.4

References

GitHub Advisory / Wiki ADVISORY
https://github.com/backstage/backstage/security/advisories/GHSA-rg9r-hr7g-5gc2
NVD — CVE-2026-106489 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-106489
Security Fix Commit FIX COMMIT
https://github.com/backstage/backstage/commit/bf6bbf7326ada7d96d7b2c4ebc4a71546106f311
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-2026-106489?
CVE-2026-106489 is a security vulnerability in Backstage involving Improper authorization enforcement for TechDocs static content under CWE-862: Missing Authorization.
Which Backstage versions are affected?
Affected versions include releases prior to 2.2.4 across affected packages: @backstage/plugin-techdocs-backend.
What version fixes CVE-2026-106489?
Upgrading to 2.2.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @backstage/plugin-techdocs-backend affected?
Yes, @backstage/plugin-techdocs-backend is affected in releases prior to 2.2.4. Upgrade your dependency to 2.2.4 or later.
What is the CVSS score of CVE-2026-106489?
CVE-2026-106489 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2026-106489?
CVE-2026-106489 is classified under CWE-862: Missing Authorization (The product does not perform an authorization check when an actor attempts to access a resource or perform an action.).
How can I check npm dependencies for CVE-2026-106489?
Run the dependency tree command: 'npm ls @backstage/plugin-techdocs-backend'. 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-rg9r-hr7g-5gc2",
  "modified" : "2026-10-07T18:00:06Z",
  "published" : "2026-10-07T18:00:06Z",
  "aliases" : [ "CVE-2026-106489" ],
  "summary" : "Backstage: Improper authorization enforcement for TechDocs static content",
  "details" : "### Impact\n\nAn authenticated user with access to one TechDocs documentation site could craft a URL able to read documentation belonging to a different entity. This only affects deployments using the external TechDocs builder with an external storage provider (S3, GCS, etc.) and the permission framework enabled. Instances that do not use the permission framework are unaffected, since TechDocs content is visible to all authenticated users by design.\n\n### Patches\n\nPatched in `@backstage/plugin-techdocs-backend` version `2.2.4`\n\n### Workarounds\n\n- None other than upgrading. Deployments that serve TechDocs from local storage are not affected.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@backstage/plugin-techdocs-backend"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.2.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/backstage/backstage/security/advisories/GHSA-rg9r-hr7g-5gc2"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-106489"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/backstage/backstage/commit/bf6bbf7326ada7d96d7b2c4ebc4a71546106f311"
  }, {
    "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-22", "CWE-862" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-07T18:00:06Z",
    "nvd_published_at" : "2026-10-06T21:17:17Z"
  }
}