CVE-2026-106506: @backstage/plugin scaffolder backend Backstage Has Improper Input Validation Vulnerability

MODERATE
Advisory Identifier: GHSA-vwp5-f99x-x3rq
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CVSS 5.3
CWE-202 CWE-203
Published
Advisory Summary

CVE-2026-106506 is a MODERATE (CVSS 5.3) backstage has improper input validation vulnerability (CWE-202: Exposure of Sensitive Information Through Data Queries) affecting @backstage/plugin scaffolder backend libraries in the npm ecosystem. The issue involves backstage has improper input validation in scaffolder task list ordering. Remediation is available by upgrading affected packages to version 4.1.0.

CVE-2026-106506 at a Glance

CVE Identifier CVE-2026-106506
GHSA Identifier GHSA-vwp5-f99x-x3rq
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-202: Exposure of Sensitive Information Through Data Queries
Affected Product @backstage/plugin scaffolder backend
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.3

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

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
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-2026-106506

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-2026-106506, 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-202: Exposure of Sensitive Information Through Data Queries, where when trying to keep information confidential, an attacker can often infer some of the information by using statistics. 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 Backstage user with permission to create and read relevant scaffolder tasks may be able to infer confidential task data under specific conditions. Successful exploitation requires retained task secrets, visibility of a target task, knowledge of the secret structure, and repeated requests. ### Patches Patched in `@backstage/plugin-scaffolder-backend` version `4.1.0` ### Workarounds - At the gateway or reverse proxy, reject task-list requests that specify custom ordering, or allow ordering only by `created_at`, `status`, and `created_by`. - Restrict scaffolder task creation and task read permissions to trusted users, preferably using owner-based task-read conditions. - Disabling task recovery can reduce secret retention after a task is claimed, but it does not protect secrets in queued tasks and should not be treated as complete mitigation.

CVE-2026-106506 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-vwp5-f99x-x3rq
NVD — CVE-2026-106506 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-106506
Security Fix Commit FIX COMMIT
https://github.com/backstage/backstage/commit/e673a869449874a9169e8f89852e75e862011b93
@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-2026-106506?
CVE-2026-106506 is a security vulnerability in @backstage/plugin scaffolder backend involving Backstage has improper input validation in scaffolder task list ordering under CWE-202: Exposure of Sensitive Information Through Data Queries.
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-2026-106506?
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-2026-106506?
CVE-2026-106506 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2026-106506?
CVE-2026-106506 is classified under CWE-202: Exposure of Sensitive Information Through Data Queries (When trying to keep information confidential, an attacker can often infer some of the information by using statistics.).
How can I check npm dependencies for CVE-2026-106506?
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-vwp5-f99x-x3rq",
  "modified" : "2026-10-07T16:24:12Z",
  "published" : "2026-10-07T16:24:12Z",
  "aliases" : [ "CVE-2026-106506" ],
  "summary" : "Backstage has improper input validation in scaffolder task list ordering",
  "details" : "### Impact\n\nAn authenticated Backstage user with permission to create and read relevant scaffolder tasks may be able to infer confidential task data under specific conditions. Successful exploitation requires retained task secrets, visibility of a target task, knowledge of the secret structure, and repeated requests.\n\n### Patches\n\nPatched in `@backstage/plugin-scaffolder-backend` version `4.1.0`\n\n### Workarounds\n\n- At the gateway or reverse proxy, reject task-list requests that specify custom ordering, or allow ordering only by `created_at`, `status`, and `created_by`.\n- Restrict scaffolder task creation and task read permissions to trusted users, preferably using owner-based task-read conditions.\n- Disabling task recovery can reduce secret retention after a task is claimed, but it does not protect secrets in queued tasks and should not be treated as complete mitigation.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/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-vwp5-f99x-x3rq"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-106506"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/backstage/backstage/commit/e673a869449874a9169e8f89852e75e862011b93"
  }, {
    "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-202", "CWE-203" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-07T16:24:12Z",
    "nvd_published_at" : "2026-10-06T22:17:05Z"
  }
}