Backstage is an open framework for building developer portals. Prior to 0.16.1 and 0.17.8, the @backstage/backend-defaults package is affected by improper preservation of access restrictions during service credential delegation. An external service credential configured with access restrictions (e.g., read-only) could bypass those restrictions by routing requests through plugin delegation paths. This could allow a restricted service to perform operations beyond its intended scope, including write operations on plugins it was restricted to read-only access for. This issue is fixed in versions 0.16.1 and 0.17.8.
Backstage is an open framework for building developer portals. Prior to 0.17.8, the @backstage/backend-defaults package is affected by improper input validation in cloud storage url readers. An attacker with write access to a cloud storage bucket used by Backstage could craft object names that could collide with protected files in the output directory. In certain deployment configurations, this could lead to content injection. This issue is fixed in version 0.17.8.
Impact
Multiple Scaffolder actions and archive extraction utilities were vulnerable to symlink-based path traversal attacks. An attacker with access to create and execute Scaffolder templates could exploit symlinks to:
1. Read arbitrary files via the debug:log action by creating a symlink pointing to sensitive files (e.g., /etc/passwd, configuration files, secrets) 2. Delete arbitrary files via the fs:delete action by creating symlinks pointing outside the workspace 3. Write files outside the workspace via archive extraction (tar/zip) containing malicious symlinks
This affects any Backstage deployment where users can create or execute Scaffolder templates.
Patches
This vulnerability is fixed in the following package versions:
- @backstage/backend-defaults version 0.12.2, 0.13.2, 0.14.1, 0.15.0 - @backstage/plugin-scaffolder-backend version 2.2.2, 3.0.2, 3.1.1 - @backstage/plugin-scaffolder-node version 0.11.2, 0.12.3
Users should upgrade to these versions or later.
Workarounds
- Follow the recommendation in the Backstage Threat Model to limit access to creating and updating templates - Restrict who can create and execute Scaffolder templates using the permissions framework - Audit existing templates for symlink usage - Run Backstage in a containerized environment with limited filesystem access
References
- CWE-59: Improper Link Resolution Before File Access - OWASP Path Traversal
Backstage is an open framework for building developer portals. Multiple Scaffolder actions and archive extraction utilities were vulnerable to symlink-based path traversal attacks. An attacker with access to create and execute Scaffolder templates could exploit symlinks to read arbitrary files via the debug:log action by creating a symlink pointing to sensitive files (e.g., /etc/passwd, configuration files, secrets); delete arbitrary files via the fs:delete action by creating symlinks pointing outside the workspace, and write files outside the workspace via archive extraction (tar/zip) containing malicious symlinks. This affects any Backstage deployment where users can create or execute Scaffolder templates. This vulnerability is fixed in @backstage/backend-defaults versions 0.12.2, 0.13.2, 0.14.1, and 0.15.0; @backstage/plugin-scaffolder-backend versions 2.2.2, 3.0.2, and 3.1.1; and @backstage/plugin-scaffolder-node versions 0.11.2 and 0.12.3. Users should upgrade to these versions or later. Some workarounds are available. Follow the recommendation in the Backstage Threat Model to limit access to creating and updating templates, restrict who can create and execute Scaffolder templates using the permissions framework, audit existing templates for symlink usage, and/or run Backstage in a containerized environment with limited filesystem access.