PT-2026-59381 · Pypi · Open-Webui

Published

2026-07-13

·

Updated

2026-07-13

CVSS v3.1

6.5

Medium

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

Vulnerability Description

In standard channels (i.e., channels whose channel.type is neither group nor dm), the endpoint
POST /api/v1/channels/{channel id}/messages/{message id}/update can be accessed with read permission only.
When access control is set to None, the authorization check has access(..., type="read") evaluates to True, allowing users who are not the message owner to update messages.
As a result, unauthorized modification of other users’ messages is possible.

Attack Prerequisites

  • The attacker is an authenticated user (role user or higher)
  • The target channel is a standard channel (i.e., not group or dm)
  • access control is None or allows read access
  • The attacker can obtain the target message id (e.g., via the channel’s message list)

Attack Scenario

  1. The attacker (User B) retrieves another user’s message id from the message list in a standard channel
  2. The attacker sends a request to
POST /api/v1/channels/{channel id}/messages/{message id}/update
  1. The message authored by another user (User A) is successfully updated

Potential Impact

  • Unauthorized modification of other users’ messages (violation of data integrity)

Steps to Reproduce

  1. Log in as an administrator
image
  1. Create User A
image
  1. Create User B
image
  1. Log in as User A
image
  1. Log in as User B
image
  1. As the administrator, create a new channel
image
  1. As User A, post a new message in the channel
image
  1. As User B, edit User A’s message
image
  1. Confirm that User A’s message has been modified without authorization
image

Affected Files and Line Numbers

  • backend/open webui/routers/channels.py:1417–1460
    The authorization check in update message by id allows access with read permission
  • backend/open webui/utils/access control.py:124–135
    When access control=None and strict=True, read access is permitted
  • backend/open webui/models/messages.py:341–358
    The update logic does not enforce any message ownership check

Recommended Mitigation

Update the condition in
backend/open webui/routers/channels.py:1451–1456
by changing the permission check from read to write, so that only administrators, message owners, or users with write permission can update messages.

Proposed Changes

  • For standard channels, change the update permission requirement from
    has access(..., type="read") to has access(..., type="write")
  • Preserve the existing ownership check (message.user id == user.id)

AI Usage

  • Translation from Japanese to English
  • CWE classification and assessment
  • Affected Files and Line Numbers

Fix

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

Related Identifiers

PYSEC-2026-2739

Affected Products

Open-Webui