CVE-2026-28788

Open WebUI's process_files_batch() endpoint missing ownership check, allows unauthorized file overwrite

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.

Affected

open-webui

CVSS v3.1 GITHUB

7.1 HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L

EPSS

0.38% chance of exploitation in the next 30 days, 31st percentile

Published

2026-03-26

Updated

2026-03-27

Proof-of-concept exploits (1)

• advisories/GHSA-jjp7-g2jw-wh3j

Security advisories

• open-webui/open-webui/security/advisories/GHSA-jjp7-g2jw-wh3j

References

• CVE Record
• NVD entry