CVE-2026-106560 in Backstage
Summary
by MITRE • 10/07/2026
Backstage is an open framework for building developer portals. Prior to 0.3.25, the @backstage/plugin-scaffolder-backend-module-confluence-to-markdown package is affected by improper repository path validation in a scaffolder backend module. An authenticated user who can execute an affected template and control its repository file location may cause generated content to be written outside the task workspace, within locations writable by the Backstage backend process. This issue is fixed in version 0.3.25.
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Analysis
by VulDB Data Team • 10/07/2026
The vulnerability identified in versions of Backstage prior to 0.3.25 represents a critical path traversal and directory escape flaw within the scaffolder backend module responsible for converting Confluence content to Markdown format. This component, specifically @backstage/plugin-scaffolder-backend-module-confluence-to-markdown, is designed to facilitate developer workflows by allowing users to generate documentation or code artifacts based on templates. However, the underlying implementation fails to adequately validate and sanitize repository paths provided during template execution. In a typical scaffolding operation, the backend process creates a temporary workspace directory where all generated files are confined. The security failure occurs when an authenticated user who possesses permission to execute specific scaffolder templates can manipulate the input parameters defining the source or destination of file operations. By supplying crafted path strings that include relative navigation sequences such as dot-dot-slash sequences, an attacker can bypass the intended confinement boundaries.
This improper validation allows for arbitrary write access outside the designated task workspace. When the backend process executes the template with these malicious inputs, it resolves the paths incorrectly and writes generated content to locations within the file system that are writable by the Backstage backend service account. This capability effectively transforms a local configuration or logic error into a significant security risk. The operational impact is severe because an attacker can overwrite existing files in sensitive directories, inject malicious scripts or configurations, or potentially achieve remote code execution if they can place executable content in locations where it will be processed by other system components. Such actions could lead to full compromise of the Backstage instance and any downstream systems that interact with its outputs.
From a classification perspective, this vulnerability aligns closely with CWE-22: Improper Limitation of a Pathname to a Restricted Directory, commonly known as path traversal. The root cause lies in insufficient sanitization of user-supplied input before it is used in file system operations. Furthermore, the exploitation vector relates to ATT&CK technique T1059, Command and Scripting Interpreter, if the written files are subsequently executed, or more broadly to lateral movement and persistence mechanisms enabled by unauthorized file writes within a privileged context. The vulnerability highlights the importance of strict input validation and the principle of least privilege in backend services that handle user-controlled data for file system interactions.
Mitigation strategies primarily involve upgrading to version 0.3.25 or later, where this path validation logic has been corrected to ensure all generated content remains strictly within the isolated task workspace. For environments unable to upgrade immediately, administrators should review scaffolder templates to restrict which parameters are user-controllable and implement additional access controls on the backend service account to limit write permissions to only essential directories. Additionally, implementing file system monitoring can help detect anomalous write activities outside expected paths, providing an early warning mechanism for potential exploitation attempts until a permanent patch is applied.