CVE-2026-106494: Backstage Improper Input Validation Vulnerability

MODERATE
Advisory Identifier: GHSA-7649-wm97-w3j3
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CVSS 4.4
CWE-73 CWE-22
Published
Advisory Summary

CVE-2026-106494 is a MODERATE (CVSS 4.4) improper input validation vulnerability (CWE-73: External Control of File Name or Path) affecting Backstage libraries in the npm ecosystem. The issue involves improper input validation in cloud storage url readers. Remediation is available by upgrading affected packages to version 0.17.8.

CVE-2026-106494 at a Glance

CVE Identifier CVE-2026-106494
GHSA Identifier GHSA-7649-wm97-w3j3
Severity MODERATE
CVSS v3.1 Base Score 4.4
CWE Classification CWE-73: External Control of File Name or Path
Affected Product Backstage
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 4.4

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

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

How to Fix CVE-2026-106494

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/backend-defaults fixed: 0.17.8 
npm install @backstage/backend-defaults@0.17.8
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/backend-defaults

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-106494, inspect your project dependencies using npm:

npm ls @backstage/backend-defaults

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 0.17.8), your application is affected.

Note: The npm ls @backstage/backend-defaults 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-73: External Control of File Name or Path, where the product allows user input to control or influence paths or file names that are used in filesystem operations. 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 attacker with write access to a cloud storage bucket used by Backstage could craft object names that could collide with protected files in the output directory. In certain deployment configurations, this could lead to content injection. ### Patches Patched in `@backstage/backend-defaults` version `0.17.8`

CVE-2026-106494 Affected Backstage Versions

1 component(s)
Fixed Versions:
0.17.8
Product / Package Ecosystem Affected Versions Fixed Version
@backstage/backend-defaults
npm/@backstage/backend-defaults
npm
< 0.17.8
0.17.8

References

GitHub Advisory / Wiki ADVISORY
https://github.com/backstage/backstage/security/advisories/GHSA-7649-wm97-w3j3
NVD — CVE-2026-106494 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-106494
Security Fix Commit FIX COMMIT
https://github.com/backstage/backstage/commit/14e925ce5b905dd8daa64c3009722febda76034c
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-2026-106494?
CVE-2026-106494 is a security vulnerability in Backstage involving Improper input validation in cloud storage URL readers under CWE-73: External Control of File Name or Path.
Which Backstage versions are affected?
Affected versions include releases prior to 0.17.8 across affected packages: @backstage/backend-defaults.
What version fixes CVE-2026-106494?
Upgrading to 0.17.8 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @backstage/backend-defaults affected?
Yes, @backstage/backend-defaults is affected in releases prior to 0.17.8. Upgrade your dependency to 0.17.8 or later.
What is the CVSS score of CVE-2026-106494?
CVE-2026-106494 has a CVSS v3.1 base score of 4.4 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N.
What CWE is associated with CVE-2026-106494?
CVE-2026-106494 is classified under CWE-73: External Control of File Name or Path (The product allows user input to control or influence paths or file names that are used in filesystem operations.).
How can I check npm dependencies for CVE-2026-106494?
Run the dependency tree command: 'npm ls @backstage/backend-defaults'. 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-7649-wm97-w3j3",
  "modified" : "2026-10-07T17:59:38Z",
  "published" : "2026-10-07T17:59:38Z",
  "aliases" : [ "CVE-2026-106494" ],
  "summary" : "Backstage: Improper input validation in cloud storage URL readers",
  "details" : "### Impact\n\nAn attacker with write access to a cloud storage bucket used by Backstage could craft object names that could collide with protected files in the output directory. In certain deployment configurations, this could lead to content injection.\n\n### Patches\n\nPatched in `@backstage/backend-defaults` version `0.17.8`",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@backstage/backend-defaults"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.17.8"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/backstage/backstage/security/advisories/GHSA-7649-wm97-w3j3"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-106494"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/backstage/backstage/commit/14e925ce5b905dd8daa64c3009722febda76034c"
  }, {
    "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-73" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-07T17:59:38Z",
    "nvd_published_at" : "2026-10-06T21:17:18Z"
  }
}