Affected: open-webui

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. Prior to 0.10.0, the file upload path accepted metadata.knowledge_id and auto-linked uploaded files to a target knowledge base without applying the write-access check used by /api/v1/knowledge//file/add, allowing read-only knowledge-base users to add arbitrary files. This issue is fixed in version 0.10.0.

Affected: PyPI: open-webui

# Open WebUI upload metadata can add files to knowledge bases without write permission

## Summary

Open WebUI's file upload background processing trusts the client-supplied `metadata.knowledge_id` value and inserts a `knowledge_file` association before validating that the uploading user has write access to the target knowledge base.

A verified user with only read access to a knowledge base can upload an arbitrary file and set `metadata={"knowledge_id":"<target knowledge id>"}`. The normal `/api/v1/knowledge/{id}/file/add` endpoint correctly requires knowledge-base write access, but the upload auto-link path bypasses that authorization check.

The immediate result is unauthorized modification of the target knowledge base's file membership. The attached attacker-controlled file becomes visible through `/api/v1/knowledge/{id}/files`, and readers/owners of that knowledge base can retrieve the file through the normal file endpoints because file access is derived from `KnowledgeFile` membership.

## Affected Version

- Repository: `open-webui/open-webui` - Tested source commit: `02dc3e689ceac915a870b373318b99c029ddf603` - Package version observed in `package.json`: `0.9.6` - Package name: `open-webui`

## Impact

A read-only knowledge-base collaborator can perform a write operation against that knowledge base by attaching arbitrary uploaded files.

Security impact:

- Unauthorized knowledge-base membership modification. - Integrity impact on shared knowledge-base file listings.…