Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to version 0.8.6, any authenticated user can overwrite any file's content by ID through the `POST /api/v1/retrieval/process/files/batch` endpoint. The endpoint performs no ownership check, so a regular user with read access to a shared knowledge base can obtain file UUIDs via `GET /api/v1/knowledge/{id}/files` and then overwrite those files, escalating from read to write. The overwritten content is served to the LLM via RAG, meaning the attacker controls what the model tells other users. Version 0.8.6 patches the issue.
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History
Fri, 27 Mar 2026 04:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to version 0.8.6, any authenticated user can overwrite any file's content by ID through the `POST /api/v1/retrieval/process/files/batch` endpoint. The endpoint performs no ownership check, so a regular user with read access to a shared knowledge base can obtain file UUIDs via `GET /api/v1/knowledge/{id}/files` and then overwrite those files, escalating from read to write. The overwritten content is served to the LLM via RAG, meaning the attacker controls what the model tells other users. Version 0.8.6 patches the issue. | |
| Title | Open WebUI's process_files_batch() endpoint missing ownership check, allows unauthorized file overwrite | |
| Weaknesses | CWE-639 | |
| References |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-03-26T23:38:20.726Z
Reserved: 2026-03-03T14:25:19.244Z
Link: CVE-2026-28788
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Status : Received
Published: 2026-03-27T00:16:22.673
Modified: 2026-03-27T00:16:22.673
Link: CVE-2026-28788
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