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CVE-2026-87994

Open WebUI: Channel members can overwrite another member's message via the chat completions endpoint

CVSS 3.1 4.3 MEDIUMCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-87994

Published

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.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-87994

Published

open-webui

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "open-webui",
                    "product": "open-webui",
                    "versions": [
                        {
                            "version": ">= 0.9.5, < 0.11.1",
                            "status": "affected"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON