CVE-2026-4400: 1millionbot Millie Chatbot

Medium severity, CVSS 6.5. EPSS: 0.3% chance of exploitation in the next 30 days.

Insecure Direct Object Reference (IDOR) vulnerability in 1millionbot Millie chat that allows private conversations of other users being viewed by simply changing the conversation ID. The vulnerability is present in the endpoint 'api.1millionbot.com/api/public/conversations/' and, if exploited, could allow a remote attacker to access other users private chatbot conversations, revealing sensitive or confidential data without requiring credentials or impersonating users. In order for the vulnerability to be exploited, the attacker must have the user's conversation ID.

Affected products

• 1millionbot Millie Chatbot: before 3.6.0 (fixed in 3.6.0)

Published 2026-03-31. Last modified 2026-06-17.