Backstage is an open framework for building developer portals

Overview

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.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.