Summary
Directus' TUS resumable upload endpoint (/files/tus) allows any authenticated user with basic file upload permissions to overwrite arbitrary existing files by UUID. The TUS controller performs only collection-level authorization checks, verifying the user has some permission on directus_files, but never validates item-level access to the specific file being replaced. As a result, row-level permission rules (e.g., "users can only update their own files") are completely bypassed via the TUS path while being correctly enforced on the standard REST upload path.
Impact
- Arbitrary file overwrite: Any authenticated user with basic TUS upload permissions can overwrite any file in
directus_files by UUID, regardless of row-level permission rules.
- Permanent data loss: The victim file's original stored bytes are deleted from storage and replaced with attacker-controlled content.
- Metadata corruption: The victim file's database record is updated with the attacker's filename, type, and size metadata.
Privilege escalation potential: If admin-owned files (e.g., application assets, templates) are stored in directus_files, a low-privilege user could replace them with malicious content.
Workaround
Disable TUS uploads by setting TUS_ENABLED=false if resumable uploads are not required.
Credit
This vulnerability was discovered and reported by bugbunny.ai.
References
bugbunny-research Reporter
Summary
Directus' TUS resumable upload endpoint (
/files/tus) allows any authenticated user with basic file upload permissions to overwrite arbitrary existing files by UUID. The TUS controller performs only collection-level authorization checks, verifying the user has some permission ondirectus_files, but never validates item-level access to the specific file being replaced. As a result, row-level permission rules (e.g., "users can only update their own files") are completely bypassed via the TUS path while being correctly enforced on the standard REST upload path.Impact
directus_filesby UUID, regardless of row-level permission rules.Privilege escalation potential: If admin-owned files (e.g., application assets, templates) are stored in
directus_files, a low-privilege user could replace them with malicious content.Workaround
Disable TUS uploads by setting
TUS_ENABLED=falseif resumable uploads are not required.Credit
This vulnerability was discovered and reported by bugbunny.ai.
References