CVE-2026-106562 in Backstage
Summary
by MITRE • 10/07/2026
Backstage is an open framework for building developer portals. Prior to 2.1.6 in @backstage/plugin-search-backend and 1.8.7 in @backstage/plugin-search-backend-module-elasticsearch, search engine permission filtering could return documents denied by policy. An authenticated Backstage user subject to a DENY policy for search document types could receive unauthorized results in deployments with permission.enabled set to true and an Elasticsearch or OpenSearch backend. This issue is fixed in @backstage/plugin-search-backend 2.1.6 and @backstage/plugin-search-backend-module-elasticsearch 1.8.7.
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Analysis
by VulDB Data Team • 10/07/2026
The vulnerability identified involves a critical authorization bypass within the Backstage developer portal framework, specifically affecting its search backend components prior to version 2.1.6 for the core plugin and 1.8.7 for the Elasticsearch module. This flaw stems from an improper implementation of access control mechanisms when interacting with external search engines such as Elasticsearch or OpenSearch. In environments where permission filtering is explicitly enabled via the configuration setting permission.enabled set to true, the system relies on policy definitions to restrict user access to specific document types and resources. However, due to a logical error in how these policies are applied during query execution against the backend database, the search functionality fails to correctly enforce DENY rules assigned to authenticated users.
From a technical perspective, this issue represents a classic case of broken access control where the application logic does not consistently validate user permissions before returning data from the underlying storage layer. When an authenticated user queries for documents that they are explicitly denied permission to view according to the configured policy, the search backend incorrectly includes these restricted items in the result set. This behavior occurs because the filtering mechanism likely applies restrictions at a different stage of the query pipeline or fails to propagate the deny directives effectively to the Elasticsearch or OpenSearch engine during the retrieval process. Consequently, sensitive information that should remain inaccessible is exposed through standard search operations, undermining the integrity of the permission model established by administrators.
The operational impact of this vulnerability is significant for organizations relying on Backstage as a central hub for developer tools and documentation. Since authenticated users can retrieve documents they are not authorized to access, there is a direct risk of information disclosure involving proprietary code repositories, internal architectural diagrams, sensitive configuration details, or confidential project roadmaps. This exposure violates the principle of least privilege and compromises data confidentiality within the organization's infrastructure. Attackers who have obtained valid credentials could exploit this flaw to gather intelligence about the company's technology stack, security configurations, and development processes without triggering typical access violation alerts, thereby facilitating further reconnaissance for more severe attacks such as targeted exploitation or social engineering campaigns.
This vulnerability aligns with CWE-284 Improper Access Control, specifically reflecting scenarios where authorization checks are bypassed during resource retrieval. In the context of the MITRE ATT&CK framework, this behavior corresponds to techniques associated with Discovery and Collection phases, particularly T1078 Valid Accounts for initial access validation and potentially T1530 Data from Cloud Storage if the search backend indexes cloud-based assets. The flaw highlights the importance of rigorous testing of permission filters in applications that aggregate data from multiple sources or rely on external databases for content delivery.
To mitigate this risk, organizations must immediately upgrade to backstage/plugin-search-backend version 2.1.6 and backstage/plugin-search-backend-module-elasticsearch version 1.8.7 or later releases where the authorization logic has been corrected to ensure that DENY policies are strictly enforced during search queries. Administrators should verify their configuration settings to confirm that permission filtering remains enabled and review audit logs for any potential unauthorized access attempts prior to patching. Additionally, implementing regular security assessments of custom plugins and backend integrations can help identify similar discrepancies in how access controls are applied across different modules within the Backstage ecosystem.