CVE-2026-106490: Backstage Improper Input Validation Vulnerability

MODERATE
Advisory Identifier: GHSA-7mfx-xg57-53c9
Share
CVSS 6.5
CWE-23 CWE-22
Published
Advisory Summary

CVE-2026-106490 is a MODERATE (CVSS 6.5) improper input validation vulnerability (CWE-23: Relative Path Traversal) affecting Backstage libraries in the npm ecosystem. The issue involves improper input validation in techdocs static content requests. Remediation is available by upgrading affected packages to version 2.2.4.

CVE-2026-106490 at a Glance

CVE Identifier CVE-2026-106490
GHSA Identifier GHSA-7mfx-xg57-53c9
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-23: Relative Path Traversal
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-2026-106490

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-2026-106490, 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-23: Relative Path Traversal, where the product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize sequences such as ".." that can resolve to a location that is outside of that directory. 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 When using the Azure Blob Storage provider, an authenticated Backstage user may be able to read restricted TechDocs content when entity-level permissions are enabled. Deployments that intentionally disable the default backend authentication policy may have broader exposure. ### Patches Patched in `@backstage/plugin-techdocs-backend` version `2.2.4` ### Workarounds - Restrict access to the TechDocs backend to users who are permitted to view all stored documentation until an upgrade can be applied. - Keep the default backend authentication policy enabled.

CVE-2026-106490 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-7mfx-xg57-53c9
NVD — CVE-2026-106490 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-106490
Security Fix Commit FIX COMMIT
https://github.com/backstage/backstage/commit/40ecc4c2e88b0218125b0a3405d1f6315b321974
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-2026-106490?
CVE-2026-106490 is a security vulnerability in Backstage involving Improper input validation in TechDocs static content requests under CWE-23: Relative Path Traversal.
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-2026-106490?
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-2026-106490?
CVE-2026-106490 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-2026-106490?
CVE-2026-106490 is classified under CWE-23: Relative Path Traversal (The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize sequences such as ".." that can resolve to a location that is outside of that directory.).
How can I check npm dependencies for CVE-2026-106490?
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-7mfx-xg57-53c9",
  "modified" : "2026-10-07T18:00:00Z",
  "published" : "2026-10-07T18:00:00Z",
  "aliases" : [ "CVE-2026-106490" ],
  "summary" : "Backstage: Improper input validation in TechDocs static content requests",
  "details" : "### Impact\n\nWhen using the Azure Blob Storage provider, an authenticated Backstage user may be able to read restricted TechDocs content when entity-level permissions are enabled. Deployments that intentionally disable the default backend authentication policy may have broader exposure.\n\n### Patches\n\nPatched in `@backstage/plugin-techdocs-backend` version `2.2.4`\n\n### Workarounds\n\n- Restrict access to the TechDocs backend to users who are permitted to view all stored documentation until an upgrade can be applied.\n- Keep the default backend authentication policy enabled.",
  "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-7mfx-xg57-53c9"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-106490"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/backstage/backstage/commit/40ecc4c2e88b0218125b0a3405d1f6315b321974"
  }, {
    "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-23" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-07T18:00:00Z",
    "nvd_published_at" : "2026-10-06T21:17:17Z"
  }
}