CVE-2026-106502 in Backstage
Summary
by MITRE • 10/07/2026
Backstage is an open framework for building developer portals. Prior to 4.1.0, the @backstage/plugin-scaffolder-backend package could expose sensitive information in Scaffolder task failure events. Under specific template and failure conditions, an authenticated user may retrieve backend-managed credentials used during task execution from affected task events. This issue is fixed in version 4.1.0.
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Analysis
by VulDB Data Team • 10/07/2026
The Backstage platform serves as a comprehensive open framework designed for constructing internal developer portals, facilitating the management of software infrastructure and services. Within this ecosystem, the scaffolder plugin plays a critical role by automating the creation of new projects or components through predefined templates. These templates often require interaction with external systems, necessitating the use of backend-managed credentials to authenticate API calls, access repositories, or provision cloud resources during the execution of scaffold tasks. The security integrity of these operations relies heavily on the secure handling and isolation of sensitive authentication data throughout the task lifecycle.
A significant vulnerability existed in versions of Backstage prior to 4.1.0 within the @backstage/plugin-scaffolder-backend package. This flaw manifested as an improper restriction of information exposure, specifically categorized under CWE-209: Generation of Error Message Containing Sensitive Information. Under specific conditions involving certain template configurations and task failure scenarios, the system failed to adequately sanitize error outputs generated during scaffolder operations. When a scaffold task encountered an error that triggered a backend exception or log entry containing authentication details, this sensitive data was inadvertently included in the event payload returned to the client side.
The operational impact of this vulnerability is severe for organizations relying on Backstage for their development workflows. An authenticated user with access to the scaffolder interface could exploit this flaw by intentionally triggering task failures designed to expose backend credentials. By inspecting the failure events or error messages associated with these tasks, an attacker could retrieve sensitive information such as API keys, service account tokens, or other secrets managed by the backend during execution. This exposure compromises the confidentiality of critical infrastructure components and potentially allows for further unauthorized access if those credentials are reused across multiple services or environments.
This vulnerability aligns with ATT&CK technique T1504: Web Service Discovery, as it involves leveraging legitimate system functions to gather sensitive configuration data that can facilitate subsequent attacks. The root cause lies in the lack of strict filtering mechanisms applied to error messages before they are serialized and transmitted back to the user interface. While Backstage is designed for developer use, assuming all users are trusted does not mitigate the risk of insider threats or compromised accounts exploiting such information leaks.
To address this issue, organizations must upgrade to version 4.1.0 or later of the @backstage/plugin-scaffolder-backend package, where the vulnerability has been resolved by implementing stricter sanitization protocols for error outputs. In addition to upgrading, it is recommended that administrators review their scaffolder templates to ensure they do not inadvertently log sensitive data during normal operations. Implementing robust logging policies that exclude secrets and credentials from standard output streams will further reduce the risk of accidental exposure. Regular security audits and penetration testing focused on information disclosure vulnerabilities should be integrated into the development lifecycle to maintain a secure developer portal environment.