CVE-2026-106503 is a high-severity (CVSS 8.1) CWE-178 vulnerability in @backstage/plugin-scaffolder-backend. A fix is available for @backstage/plugin-scaffolder-backend — see the affected versions and patch details below.
Backstage: Scaffolder action input authorization bypass
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-106503.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-106503 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
@backstage/plugin-scaffolder-backend📦@backstage/plugin-scaffolder-backend📦@backstage/plugin-scaffolder-backend📦@backstage/plugin-scaffolder-backendReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
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 scaffolder action input authorization bypass. An authenticated user with access to affected Scaffolder templates could bypass configured action restrictions. Depending on integration credentials, this could grant unauthorized access to repositories and related source-control resources. This issue is fixed in versions 3.3.1, 3.4.1, 4.0.3 and 4.1.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @backstage/plugin-scaffolder-backend | all versions | 3.3.1npm install @backstage/plugin-scaffolder-backend@3.3.1 |
| 📦npm | @backstage/plugin-scaffolder-backend | ≥ 3.4.0&&< 3.4.1 | 3.4.1npm install @backstage/plugin-scaffolder-backend@3.4.1 |
| 📦npm | @backstage/plugin-scaffolder-backend | ≥ 4.0.0&&< 4.0.3 | 4.0.3npm install @backstage/plugin-scaffolder-backend@4.0.3 |
| 📦npm | @backstage/plugin-scaffolder-backend | ≥ 4.0.4&&< 4.1.0 | 4.1.0npm install @backstage/plugin-scaffolder-backend@4.1.0 |
Affected Products
backstagelinuxfoundationbackstage\/plugin-scaffolder-backendlinuxfoundationDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @backstage/plugin-scaffolder-backend, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @backstage/plugin-scaffolder-backend to 3.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-106503 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability is rated as an Important severity because authenticated remote users can circumvent execution guardrails defined for backend actions, creating high confidentiality and integrity risks for connected source control management systems. In Red Hat Developer Hub and Ansible Automation Platform…
To reduce the risk associated with this flaw: 1. Restrict template access: Limit permissions to execute Scaffolder templates to trusted users by configuring role-based access control (RBAC) policies in Red Hat Developer Hub or Ansible Automation Platform. 2. Enforce least privilege on integration credentials: Audit and restrict source control provider tokens (such as GitHub, GitLab, or Bitbucket credentials) to the minimum necessary repository scopes and permissions required for legitimate template actions. Caveats: Limiting integration credential permissions may cause templates that require administrative or elevated privileges to fail. Modifying credential secrets or configuration files…Source: Red Hat security advisory for CVE-2026-106503 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Ansible Automation Platform 2.2 | ansible-automation-platform/automation-portal:1792523640 | RHSA-2026:86675 |
Frequently Asked Questions
Is CVE-2026-106503 in your dependencies?
Find it across npm, including transitive dependencies.