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CVE-2026-106495 stems from an improper access control flaw residing within the backend action invocation handling of the Backstage framework, specifically affecting the `@backstage/backend-defaults` package prior to version 0.17.8. In a standard configuration, system operators can explicitly disable or exclude specific backend actions through administrative configuration files to restrict functionality. However, due to insufficient permission validation checks during the invocation phase, an authenticated user is capable of directly invoking these operator-excluded actions. Although downstream authorization checks and existing action-level permissions remain active and enforced, the ability to bypass the configuration-level exclusion list introduces a security gap where unauthorized workflows can be triggered by standard users. This can lead to unexpected operational behavior or processing tasks that were intended to be permanently disabled by administrators within the developer portal ecosystem.
DailyCVE Form:
Platform: Backstage
Version: <0.17.8
Vulnerability : Improper Access
Severity: Medium
date: 2026-10-12
Prediction: 2026-10-15
What Undercode Say:
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Analysis reveals that the vulnerability arises from a missing validation check on configuration filters during action dispatch routines. When handling backend requests, the endpoint fails to properly cross-reference the requested action identifier against the global operator exclusion list before execution handover.
Exploit: (Educational Purposes!)
curl -X POST 'https://backstage-instance/api/actions/invoke' \
-H 'Authorization: Bearer <USER_TOKEN>' \
-H 'Content-Type: application/json' \
-d '{"actionId": "excluded-operator-action", "payload": {}}'
Protection: from this CVE
Upgrade the `@backstage/backend-defaults` package to version 0.17.8 or higher, and restrict network-level access to backend action invocation endpoints to trusted callers only.
Impact
Authenticated users can execute backend actions that administrators explicitly excluded via configuration, potentially triggering restricted internal routines.
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Sources:
Reported By: github.com
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