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Vulnerability · Published Oct 6, 2026 · Assigned by GitHub_M

CVE-2026-106500Backstage: Improper task state validation in Scaffolder backend

High 8.5

In plain English

A high-severity race condition in backstage from backstage. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.5High
Exploit odds (30 days)0.3%top 72.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

Backstage is an open framework for building developer portals. Prior to 3.3.1, 3.4.1, 4.0.3 and 4.1.0, the @backstage/plugin-scaffolder-backend package is affected by improper task state validation in scaffolder backend. An 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. This issue is fixed in versions 3.3.1, 3.4.1, 4.0.3 and 4.1.0.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
npm@backstage/plugin-scaffolder-backend4.1.0GHSA-xvgh-hmx8-9xxf

Affected products (as reported)

VendorProductVersions
backstage backstage < 1.49.6>= 1.50.0-next.0, < 1.50.5>= 1.51.0-next.0, < 1.54.6
@backstage plugin-scaffolder-backend < 3.3.1>= 3.4.0, < 3.4.1>= 4.0.0, < 4.0.3>= 4.0.4, < 4.1.0

Weakness: CWE-59, CWE-362 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

References