EUVD-2026-16482
GHSA-jjp7-g2jw-wh3j
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
Lifecycle Timeline
4Description
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.
Analysis
Open WebUI versions prior to 0.8.6 permit authenticated users to overwrite arbitrary file contents through an insecure batch processing endpoint, escalating read-only knowledge base access to write permissions without ownership validation. Attackers with low-level privileges can manipulate RAG (Retrieval-Augmented Generation) content served to language models, poisoning AI responses delivered to other users. …
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Remediation
Within 24 hours: Identify all Open WebUI deployments and document current versions in use. Within 7 days: Upgrade all instances to version 0.8.6 or later when released; if unavailable, implement network access restrictions to the batch processing endpoint and enforce role-based access control limiting knowledge base write permissions to administrators only. …
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External POC / Exploit Code
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