CVE-2026-106500: Backstage Improper Task State Validation Vulnerability
HIGHCVE-2026-106500 is a HIGH (CVSS 8.5) improper task state validation vulnerability (CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')) affecting Backstage libraries in the npm ecosystem. The issue involves improper task state validation in scaffolder backend. Remediation is available by upgrading affected packages to version 4.1.0.
CVE-2026-106500 at a Glance
Security Impact
CVSS: 8.5
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:C/C:H/I:H/A:H).
How to Fix CVE-2026-106500
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.
npm install @backstage/plugin-scaffolder-backend@4.1.0Run the following command in your project directory to verify that all resolved dependencies use the patched release:
npm ls @backstage/plugin-scaffolder-backendHow to Check if You Are Affected
To determine whether your Node.js application is affected by CVE-2026-106500, inspect your project dependencies using npm:
npm ls @backstage/plugin-scaffolder-backendAnalyze 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 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-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition'), where the product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently. 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
CVE-2026-106500 Affected Backstage Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
@backstage/plugin-scaffolder-backend
|
npm |
< 4.1.0
|
4.1.0
|
References
Frequently Asked Questions
What is CVE-2026-106500?
Which Backstage versions are affected?
What version fixes CVE-2026-106500?
Is @backstage/plugin-scaffolder-backend affected?
What is the CVSS score of CVE-2026-106500?
What CWE is associated with CVE-2026-106500?
How can I check npm dependencies for CVE-2026-106500?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-xvgh-hmx8-9xxf",
"modified" : "2026-10-07T17:59:02Z",
"published" : "2026-10-07T17:59:02Z",
"aliases" : [ "CVE-2026-106500" ],
"summary" : "Backstage: Improper task state validation in Scaffolder backend",
"details" : "### Impact\n\nAn authenticated user with permission to create and access Scaffolder tasks may, under specific timing and deployment conditions, affect files accessible to the Backstage backend. If backend application files are writable, the confidentiality, integrity, and availability of the backend may be compromised.\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-read permissions to trusted users through the permission policy.\n- Limit who can register or modify templates and which Scaffolder actions may execute.\n- Run backend application files read-only outside a dedicated, least-privilege Scaffolder working directory.\n\n### References\n\n- [Authorizing Scaffolder tasks, parameters, steps, and actions](https://backstage.io/docs/features/software-templates/authorizing-scaffolder-template-details/)",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H"
} ],
"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-xvgh-hmx8-9xxf"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-106500"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/commit/0d24f1b8701f3dde6cd597f81997c1ea873a43ae"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/commit/56be299dd3ef6706e13e76ea2f8a9b0dd0b6413d"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/commit/9e86c95a1a3ddfd54db03731cd8678aa63495175"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/backstage/backstage"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/releases/tag/v1.49.6"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/releases/tag/v1.50.5"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/releases/tag/v1.54.6"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-362", "CWE-59" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2026-10-07T17:59:02Z",
"nvd_published_at" : "2026-10-06T22:17:05Z"
}
}