CVE-2026-54007

Open WebUI: Cross-origin postMessage confirmation bypass via action:submit

State: Published
Severity: 7.1 High
Published: Jun 23, 2026
Updated: Jun 26, 2026
Reserved: Jun 11, 2026

Description

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.6, the chat message listener allows non-same-origin input:prompt and action:submit messages, so an external site can set prompt text and trigger submitPrompt() in an authenticated victim session. I validated this with a cross-origin attacker page that auto-posted messages and caused unauthorized POST /api/v1/chats/new and POST /api/chat/completions requests containing attacker-controlled prompts. This enables cross-site forced actions and model/tool execution under victim privileges without consent. This vulnerability is fixed in 0.9.6.

Scores

CVSS	Score	Vector	Source
4.0	7.1 High	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N	GitHub_M

Weaknesses

CWE-346 Origin Validation Error

Affected Products

Product	Versions
open-webuiopen-webui	< 0.9.6Affected

References

https://github.com/open-webui/open-webui/security/advisories/GHSA-3vv5-8xxp-4f55

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