CVE-2018-1000503: Mybb

Medium severity, CVSS 4.3. EPSS: 0.6% chance of exploitation in the next 30 days.

MyBB Group MyBB contains a Incorrect Access Control vulnerability in Private forums that can result in Users can view posts from private forums without having the password. This attack appear to be exploitable via Subscribe to a forum through IDOR. This vulnerability appears to have been fixed in 1.8.15.

Affected products

• Mybb Mybb: before 1.8.15 (fixed in 1.8.15)

Published 2018-06-26. Last modified 2026-06-17.