What’s Vulnerable › Vulnerabilities
CVE-2026-28788: Open WebUI's process_files_batch() endpoint missing ownership check, allows unauthorized file overwrite
- Severity: high (CVSS 7.1 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 3.0% probability of exploitation in the next 30 days
- Public exploit or detection template: yes
- Published: 2026-03-27 · updated 2026-06-17
- Weakness: CWE-639
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.
Affected products
- open-webui: before 0.8.6 — fixed in 0.8.6
How to fix
Upgrade to a fixed version: open-webui 0.8.6. Check the vendor advisory for mitigations.
References
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