CVE-2026-106506 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 is affected by improper input validation in scaffolder task list ordering. An authenticated Backstage user with permission to create and read relevant scaffolder tasks may be able to infer confidential task data under specific conditions. Successful exploitation requires retained task secrets, visibility of a target task, knowledge of the secret structure, and repeated requests. This issue is fixed in version 4.1.0.
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Analysis
by VulDB Data Team • 10/07/2026
The Backstage developer portal framework contains a vulnerability within its scaffolder backend component that allows for information disclosure through improper input validation regarding task list ordering. Prior to version 4.1.0, the @backstage/plugin-scaffolder-backend package failed to adequately sanitize or validate inputs related to how scaffold tasks are ordered and retrieved from the database. This flaw creates a side-channel attack vector where an authenticated user with permissions to create and read scaffolder tasks can exploit timing differences or error responses associated with specific ordering parameters to infer sensitive data that should otherwise remain confidential. The vulnerability stems from the backend logic not properly isolating task metadata when processing requests for ordered lists, allowing attackers to probe the system's internal state through carefully crafted queries.
Successful exploitation of this flaw requires a combination of several conditions to be met simultaneously. First, the attacker must possess valid authentication credentials and have explicit permissions to create and read scaffolder tasks within the Backstage instance. Second, there must be retained task secrets stored in the backend database that are accessible via these endpoints. Third, the target task containing sensitive information must be visible or queryable by the authenticated user. Fourth, the attacker must possess knowledge of the internal secret structure used by the application to store and reference tasks. Finally, exploitation relies on making repeated requests with varying ordering parameters to observe subtle differences in response times or error messages that reveal whether specific characters or values exist within the hidden task data. This constitutes a classic time-based blind injection scenario where the lack of proper input validation allows for systematic enumeration of sensitive fields.
The operational impact of this vulnerability is significant, as it enables an authenticated user with relatively low privileges to extract confidential scaffolder configuration details and secrets. These secrets may include API keys, repository credentials, or other authentication tokens required by backend services invoked during task execution. The ability to infer these values without direct access to the database undermines the principle of least privilege and compromises the security boundary between different users within the developer portal. This exposure can lead to further unauthorized access to internal systems if the extracted secrets are reused elsewhere in the organization's infrastructure, potentially escalating from information disclosure to full system compromise depending on the scope of the leaked credentials.
This vulnerability is categorized under CWE-209 as an Information Exposure Through an Error Message and aligns with ATT&CK technique T1530, which involves Data from Cloud Storage Object Discovery or similar data exfiltration methods via application logic flaws. The root cause lies in CWE-602, Client-Side Enforcement of Server-Side Security Controls, where the backend relies on client-supplied ordering parameters without sufficient validation against expected input ranges and types. To mitigate this risk, organizations running Backstage prior to version 4.1.0 must upgrade immediately to the patched release which addresses the improper input validation in scaffolder task list ordering. Additionally, administrators should enforce strict least-privilege access controls for scaffolder tasks, rotate any secrets that may have been exposed during periods of vulnerability exposure, and implement rate limiting on API endpoints to mitigate the effectiveness of repeated probing requests used in such enumeration attacks.