High (7.1). EPSS 0.5% chance of exploitation in the next 30 days. Fixed in open-webui 0.10.0.
Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.5 before 0.10.0, any authenticated user can overwrite the content of a message in a channel they do not belong to (including private and DM channels) by sending a chat completion request with a channel:-prefixed chat_id and a target message_id. The channel: path routes pipeline output through _make_channel_emitter, which writes to the Messages table using the caller-supplied message_id without binding it to the channel. This issue is fixed in version 0.10.0.
Severity
CVSS 3.1
7.1 high
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
EPSS
0.5% chance of exploitation in the next 30 days; higher than 41% of CVEs (scores of 2026-10-31)