CVE-2026-54007: Open WebUI: Cross-origin postMessage confirmation bypass via action:submit

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-06-23 · updated 2026-06-26
Weakness: CWE-346

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.

Affected products

open-webui: before 0.9.6 — fixed in 0.9.6

How to fix

Upgrade to a fixed version: open-webui 0.9.6. Check the vendor advisory for mitigations.

References

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