CVE-2026-106500

Backstage: Improper task state validation in Scaffolder backend

Workarounds

• Restrict Scaffolder task creation and task-read permissions to trusted users through the permission policy.
• Limit who can register or modify templates and which Scaffolder actions may execute.
• Run backend application files read-only outside a dedicated, least-privilege Scaffolder working directory.

References

• Authorizing Scaffolder tasks, parameters, steps, and actions

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.

Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing. Typical impact: TOCTOU exploits, data corruption, or privilege escalation.

CVE-2026-106500 has a CVSS score of 8.5 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.1.0); upgrading removes the vulnerable code path.

Kodem intelligence

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Patched in @backstage/plugin-scaffolder-backend version 4.1.0

1. What is CVE-2026-106500? CVE-2026-106500 is a high-severity race condition vulnerability in @backstage/plugin-scaffolder-backend (npm), affecting versions < 4.1.0. It is fixed in 4.1.0. Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing.
2. How severe is CVE-2026-106500? CVE-2026-106500 has a CVSS score of 8.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of @backstage/plugin-scaffolder-backend are affected by CVE-2026-106500? @backstage/plugin-scaffolder-backend (npm) versions < 4.1.0 is affected.
4. Is there a fix for CVE-2026-106500? Yes. CVE-2026-106500 is fixed in 4.1.0. Upgrade to this version or later.
5. Is CVE-2026-106500 exploitable, and should I be worried? Whether CVE-2026-106500 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-106500 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-106500? Upgrade @backstage/plugin-scaffolder-backend to 4.1.0 or later.

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