Impact
An authenticated user could invoke actions that an operator had excluded through action configuration. Existing action permissions and downstream authorization remain enforced.
Patches
Patched in @backstage/backend-defaults version 0.17.8
Workarounds
Limit access to action invocation endpoints to trusted service callers until upgrading.
Impact
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.
Patches
Patched in @backstage/backend-defaults version 0.17.8
Impact
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.
Patches
Patched in @backstage/backend-defaults version 0.17.8
Workarounds
If you're unable to upgrade immediately:
- If practical, replace restricted credentials with separate, purpose-specific unrestricted credentials scoped to trusted consumers. - Restrict network-level access to Backstage backend API endpoints to trusted callers only.
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.
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