CVE-2026-28788
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.86%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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
- 7.1 HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
- EPSS
- 2.86% probability · 86th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-639
- Affected
- openwebui/open webui
- Source
- security-advisories@github.com
References
- https://github.com/open-webui/open-webui/security/advisories/GHSA-jjp7-g2jw-wh3jExploit, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.