CVE-2026-87994
Received
Received - Intake
Message Alteration via Chat Completion in Open WebUI
Vulnerability report for CVE-2026-87994, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-09-09
Last updated on: 2026-09-09
Assigner: GitHub, Inc.
Description
Description
Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.5 until 0.11.1, the channel branch of chat_completion in backend/open_webui/main.py checked channel write access and channel membership for a supplied message_id but did not verify that the calling user authored the targeted message. A channel member could use the chat completions endpoint to replace another member's message while preserving the victim as the stored author, altering the conversation record without gaining access to other channels. This issue is fixed in version 0.11.1.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| open_webui | open_webui | From 0.9.5 (inc) to 0.11.1 (inc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-862 | The product does not perform an authorization check when an actor attempts to access a resource or perform an action. |
| CWE-639 | The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. |
