CVE-2026-106504: @backstage/plugin scaffolder backend Backstage Has Sensitive Information Exposure Vulnerability

MODERATE
Advisory Identifier: GHSA-4xvq-3m68-h444
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CVSS 6.5
CWE-532
Published
Advisory Summary

CVE-2026-106504 is a MODERATE (CVSS 6.5) backstage has sensitive information exposure vulnerability (CWE-532: Insertion of Sensitive Information into Log File) affecting @backstage/plugin scaffolder backend libraries in the npm ecosystem. The issue involves backstage has sensitive information exposure in scaffolder task logs. Remediation is available by upgrading affected packages to version 4.1.0.

CVE-2026-106504 at a Glance

CVE Identifier CVE-2026-106504
GHSA Identifier GHSA-4xvq-3m68-h444
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-532: Insertion of Sensitive Information into Log File
Affected Product @backstage/plugin scaffolder backend
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-2026-106504

To remediate this vulnerability, upgrade all affected @backstage/plugin scaffolder 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.

@backstage/plugin-scaffolder-backend fixed: 4.1.0 
npm install @backstage/plugin-scaffolder-backend@4.1.0
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-scaffolder-backend

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-106504, inspect your project dependencies using npm:

npm ls @backstage/plugin-scaffolder-backend

Analyze the terminal output to locate any version of @backstage/plugin scaffolder backend in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.1.0), your application is affected.

Note: The npm ls @backstage/plugin-scaffolder-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-532: Insertion of Sensitive Information into Log File, where the product writes sensitive information to a log file. In @backstage/plugin scaffolder 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

### Impact An authenticated user who can create and read scaffolder tasks may be able to observe sensitive values in task logs in deployments with restrictive action permissions and affected templates. Exploitation requires a denied action whose input contains such a value. ### Patches Patched in `@backstage/plugin-scaffolder-backend` version `4.1.0` ### Workarounds - Restrict scaffolder task creation and task-log reading to trusted users. - Avoid placing centrally managed sensitive values in inputs to actions that may be denied until upgrading. ### References - [Backstage threat model](https://backstage.io/docs/overview/threat-model/) - [Backstage permissions overview](https://backstage.io/docs/permissions/overview/)

CVE-2026-106504 Affected @backstage/plugin scaffolder backend Versions

1 component(s)
Fixed Versions:
4.1.0
Product / Package Ecosystem Affected Versions Fixed Version
@backstage/plugin-scaffolder-backend
npm/@backstage/plugin-scaffolder-backend
npm
< 4.1.0
4.1.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/backstage/backstage/security/advisories/GHSA-4xvq-3m68-h444
NVD — CVE-2026-106504 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-106504
Security Fix Commit FIX COMMIT
https://github.com/backstage/backstage/commit/3eb3dc59eb0da0deccd532f19eb460bb452c9efb
@backstage/plugin scaffolder backend Source Repository REPOSITORY
https://github.com/backstage/backstage
@backstage/plugin scaffolder backend Release RELEASE
https://github.com/backstage/backstage/releases/tag/v1.54.6

Frequently Asked Questions

What is CVE-2026-106504?
CVE-2026-106504 is a security vulnerability in @backstage/plugin scaffolder backend involving Backstage has sensitive information exposure in scaffolder task logs under CWE-532: Insertion of Sensitive Information into Log File.
Which @backstage/plugin scaffolder backend versions are affected?
Affected versions include releases prior to 4.1.0 across affected packages: @backstage/plugin-scaffolder-backend.
What version fixes CVE-2026-106504?
Upgrading to 4.1.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @backstage/plugin-scaffolder-backend affected?
Yes, @backstage/plugin-scaffolder-backend is affected in releases prior to 4.1.0. Upgrade your dependency to 4.1.0 or later.
What is the CVSS score of CVE-2026-106504?
CVE-2026-106504 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-2026-106504?
CVE-2026-106504 is classified under CWE-532: Insertion of Sensitive Information into Log File (The product writes sensitive information to a log file.).
How can I check npm dependencies for CVE-2026-106504?
Run the dependency tree command: 'npm ls @backstage/plugin-scaffolder-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-4xvq-3m68-h444",
  "modified" : "2026-10-07T16:24:29Z",
  "published" : "2026-10-07T16:24:29Z",
  "aliases" : [ "CVE-2026-106504" ],
  "summary" : "Backstage has sensitive information exposure in scaffolder task logs",
  "details" : "### Impact\n\nAn authenticated user who can create and read scaffolder tasks may be able to observe sensitive values in task logs in deployments with restrictive action permissions and affected templates. Exploitation requires a denied action whose input contains such a value.\n\n### Patches\n\nPatched in `@backstage/plugin-scaffolder-backend` version `4.1.0`\n\n### Workarounds\n\n- Restrict scaffolder task creation and task-log reading to trusted users.\n- Avoid placing centrally managed sensitive values in inputs to actions that may be denied until upgrading.\n\n### References\n\n- [Backstage threat model](https://backstage.io/docs/overview/threat-model/)\n- [Backstage permissions overview](https://backstage.io/docs/permissions/overview/)",
  "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-scaffolder-backend"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.1.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/backstage/backstage/security/advisories/GHSA-4xvq-3m68-h444"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-106504"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/backstage/backstage/commit/3eb3dc59eb0da0deccd532f19eb460bb452c9efb"
  }, {
    "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-532" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-07T16:24:29Z",
    "nvd_published_at" : "2026-10-06T22:17:05Z"
  }
}