Auth bypass in 1millionbot Millie Chat
CVE-2026-4400
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.
Vulnerability class: IDOR (Insecure Direct Object Reference)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (23.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 24th percentile — 23.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
- 1millionbot Millie Chat — versions 3.6.0
- 1millionbot Millie Chatbot
Weakness classification (CWE)
References
- www.incibe.es/en/incibe-cert/notices/aviso/multiple-vulnerabilities-1millionbot… (Third Party Advisory)
Frequently asked questions
- What is CVE-2026-4400?
- CVE-2026-4400 is a medium-severity vulnerability in 1millionbot Millie Chat, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 6.5/10. Published 2026-03-31.
- How severe is CVE-2026-4400?
- Medium severity. CVSS v3 base score is 6.5 out of 10.