CVE-2026-28788

High

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.

SeverityHigh

CVSS7.1

Exploit probability—

ProductOpenwebui Open Webui

PublishedMar 27, 2026

First seenMar 27, 2026

Weakness typeCWE-639Authorization bypass through user-controlled key

How to fix

Update

openwebui open_webui0.8.6 or later
open-webui0.8.6 or later

Affected products

Product	Affected versions	Fixed in
openwebui open_webui	v < 0.8.6	0.8.6
open-webuiPyPI	v < 0.8.6	0.8.6

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