CVE-2026-28788
Severity CVSS v4.0:
Pending analysis
Type:
Unavailable / Other
Publication date:
27/03/2026
Last modified:
27/03/2026
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.
Impact
Base Score 3.x
7.10
Severity 3.x
HIGH