CVE-2026-28788
Open WebUI's process_files_batch() endpoint missing ownership check, allows unauthorized file overwrite
In short
Open WebUI allows any logged-in user to overwrite files they should only be able to read, by guessing or discovering file IDs. An attacker can change file contents to trick the AI into giving false information to other users.
Technical detail
The `POST /api/v1/retrieval/process/files/batch` endpoint lacks authorization checks on file ownership, permitting authenticated users to modify arbitrary files via their UUIDs. An attacker can enumerate file IDs through `GET /api/v1/knowledge/{id}/files` and overwrite content served to the LLM via RAG, achieving privilege escalation from read to write access and information manipulation.
Summary generated and translated by AI from the official 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.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
Affected products
open-webui · open-webuiWant to know if your infrastructure is exposed to this?
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