CVE-2026-70481: Open WebUI improper authorization in standard channel message handlers

Executive brief

Open WebUI is a user interface for interacting with large language models. A vulnerability in its messaging system allowed any user with write access to a standard channel to edit or delete messages sent by other users. This could lead to the forgery of communications under another person's name or the destruction of important conversation records within shared channels.

Technical details

An authorization bypass exists in Open WebUI's standard channel message handlers. The `update_message_by_id` and `delete_message_by_id` functions in `backend/open_webui/routers/channels.py` failed to verify message authorship for 'standard' type channels, instead only checking if the requester had general write permissions for the channel. An authenticated attacker with basic user privileges and write access to a channel could modify the content, metadata, and data payloads of any message in that channel, or delete messages entirely. This vulnerability was fixed in version 0.11.0 by unifying the authorship checks across all channel types.

Affected products

• Open WebUI open-webui >= 0.5.0, <= 0.10.2

Timeline

• 2026-08-02: advisory: Initial advisory published by maintainers
• 2026-08-04: patched: Version 0.11.0 released with fix

References

• https://api.github.com/users/Foxer131
• https://github.com/Foxer131
• https://api.github.com/users/Foxer131/gists%7B/gist_id%7D
• https://api.github.com/users/Foxer131/repos
• https://avatars.githubusercontent.com/u/193660555?v=4
• https://api.github.com/users/Foxer131/events%7B/privacy%7D