GHSA-824x-88xg-cwrv Redaxo has Path Traversal in Backup Addon Leading to Arbitrary File Read

• Packagist redaxo/source: < 5.20.2 → fixed in 5.20.2

Summary Authenticated users with backup permissions can read arbitrary files within the webroot via path traversal in the Backup addon's file export functionality. Details The Backup addon does not validate the `EXPDIR` POST parameter against the UI-generated allowlist of permitted directories. An attacker can supply relative paths containing `../` sequences (or even absolute paths inside the document root) to include any readable file in the generated `.tar.gz` archive. Vulnerable code: • `redaxo/src/addons/backup/pages/export.php` (lines 72-76) – directly uses `$_POST['EXPDIR']` • `redaxo/src/addons/backup/lib/backup.php` (lines ~413 & ~427) – concatenates unsanitized user input with base path This allows disclosure of sensitive files such as: • `redaxo/data/core/config.yml` → database credentials + password hashes of all backend users • `.env`, custom configuration files, logs, uploaded malicious files, etc. Affected versions ≤ 5.20.1 (confirmed working) Patched versions None (as of 2025-12-09) PoC – Extracting database credentials and password hashes 1. Log in as any user with Backup permission 2. Go to Backup → Export → Files 3. Intercept the request with Burp Suite 4. Change one `EXPDIR[]` value to `../../../../var/www/html/redaxo/data/core` 5. Send request → download archive 6. Extract and open `data/core/config.yml` Result: plaintext database password Impact Full compromise of the REDAXO installation: • Database takeover • Password hash extraction → offline cracking → admin access • When combined with other vulnerabilities → RCE CVSS 4.0 vector & score below. Credits Discovered by: Łukasz Rybak