GHSA-rq6q-wr2q-7pgp Backstage has a Possible Symlink Path Traversal in Scaffolder Actions

• npm @backstage/backend-defaults: < 0.12.2 → fixed in 0.12.2 • npm @backstage/backend-defaults: >= 0.13.0, < 0.13.2 → fixed in 0.13.2 • npm @backstage/backend-defaults: >= 0.14.0, < 0.14.1 → fixed in 0.14.1 • npm @backstage/plugin-scaffolder-backend: < 2.2.2 → fixed in 2.2.2 • npm @backstage/plugin-scaffolder-backend: >= 3.0.0, < 3.0.2 → fixed in 3.0.2 • npm @backstage/plugin-scaffolder-backend: >= 3.1.0, < 3.1.1 → fixed in 3.1.1 • npm @backstage/plugin-scaffolder-node: < 0.11.2 → fixed in 0.11.2 • npm @backstage/plugin-scaffolder-node: >= 0.12.0, < 0.12.3 → fixed in 0.12.3

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