Open WebUI: Channel members can overwrite another member's message via the chat completions endpoint
cve-program · CVE-2026-87994
PublishedOpen 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.
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cve-program · CVE-2026-87994
PublishedOpen WebUI: Channel members can overwrite another member's message via the chat completions endpoint
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.
- Source published
- 9 Sep 2026 21:24:55 UTC
- Source modified
- 10 Sep 2026 15:59:55 UTC
- Saved here
- 23 Oct 2026 15:48:27 UTC
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CVSS 3.1 · 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N