[PR #24725] fix: gate chat_completion channel: branch on channel access + message scoping #115113

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GiteaMirror · 2026-05-18T16:04:10-05:00

GiteaMirror commented

2026-05-18 16:04:10 -05:00

📋 Pull Request Information

Original PR: https://github.com/open-webui/open-webui/pull/24725
Author: @Classic298
Created: 5/14/2026
Status: 🔄 Open

Base: dev ← Head: fix/channel-chat-id-membership-and-message-scoping

📝 Commits (2)

30bd3cc fix: gate chat_completion channel: branch on channel access + message scoping
6f27df8 chore: trim verbose comment on channel: branch gate

📊 Changes

1 file changed (+41 additions, -0 deletions)

View changed files

📝 backend/open_webui/main.py (+41 -0)

📄 Description

When chat_id starts with 'channel:' the chat-completion handler skips the chat ownership / storage block below it. Nothing replaced that gate. The downstream channel emitter in socket/main.py:make_channel emitter writes to Messages.update_message_by_id using a caller-supplied message_id pulled from form_data['id'], with no membership check, no write-access check, and no validation that the message_id belongs to the channel.

Net effect: any authenticated user could submit
chat_id='channel:' + id='' and overwrite that message with attacker-controlled LLM output. Cross- channel writes worked too — private channels, DMs, channels the caller has no access to. Original author attribution stayed intact on the overwritten row.

Add the missing checks at the channel: branch:

Channel must exist (404 otherwise).
Non-admin caller must have write access to the channel — membership for group/dm channels, AccessGrants permission='write' for others.
The message_id (if supplied) must belong to the same channel — a caller with write access to channel A cannot use this path to overwrite a message in channel B.

Behaviour change is limited to callers who were exploiting the gap: legitimate flows that supply a message_id under their own channel membership continue to work unchanged.

Contributor License Agreement

By submitting this pull request, I confirm that I have read and fully agree to the Contributor License Agreement (CLA), and I am providing my contributions under its terms.

Note

Deleting the CLA section will lead to immediate closure of your PR and it will not be merged in.

_{🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.}

## 📋 Pull Request Information **Original PR:** https://github.com/open-webui/open-webui/pull/24725 **Author:** [@Classic298](https://github.com/Classic298) **Created:** 5/14/2026 **Status:** 🔄 Open **Base:** `dev` ← **Head:** `fix/channel-chat-id-membership-and-message-scoping` --- ### 📝 Commits (2) - [`30bd3cc`](https://github.com/open-webui/open-webui/commit/30bd3cc2180f63fa44393bb42e58cfc172d7b481) fix: gate chat_completion channel: branch on channel access + message scoping - [`6f27df8`](https://github.com/open-webui/open-webui/commit/6f27df88d58ac7649d1f484b5de0db440a72e4a0) chore: trim verbose comment on channel: branch gate ### 📊 Changes **1 file changed** (+41 additions, -0 deletions) <details> <summary>View changed files</summary> 📝 `backend/open_webui/main.py` (+41 -0) </details> ### 📄 Description When chat_id starts with 'channel:' the chat-completion handler skips the chat ownership / storage block below it. Nothing replaced that gate. The downstream channel emitter in socket/main.py:_make_channel_ emitter writes to Messages.update_message_by_id using a caller-supplied message_id pulled from form_data['id'], with no membership check, no write-access check, and no validation that the message_id belongs to the channel. Net effect: any authenticated user could submit chat_id='channel:<any-channel-uuid>' + id='<any-message-uuid>' and overwrite that message with attacker-controlled LLM output. Cross- channel writes worked too — private channels, DMs, channels the caller has no access to. Original author attribution stayed intact on the overwritten row. Add the missing checks at the channel: branch: 1. Channel must exist (404 otherwise). 2. Non-admin caller must have write access to the channel — membership for group/dm channels, AccessGrants permission='write' for others. 3. The message_id (if supplied) must belong to the same channel — a caller with write access to channel A cannot use this path to overwrite a message in channel B. Behaviour change is limited to callers who were exploiting the gap: legitimate flows that supply a message_id under their own channel membership continue to work unchanged. ### Contributor License Agreement  - [x] By submitting this pull request, I confirm that I have read and fully agree to the [Contributor License Agreement (CLA)](https://github.com/open-webui/open-webui/blob/main/CONTRIBUTOR_LICENSE_AGREEMENT), and I am providing my contributions under its terms. > [!NOTE] > Deleting the CLA section will lead to immediate closure of your PR and it will not be merged in. --- <sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>

GiteaMirror added the pull-request label 2026-05-18 16:04:10 -05:00

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Reference: github-starred/open-webui#115113