CVE-2026-45121

MyBB is free and open source forum software. Prior to 1.8.40, the calendar module does not check permissions consistently when listing calendars, allowing authenticated users to access titles of calendars that are otherwise inaccessible. The affected calendar-selection paths in calendar.php perfo...

CVE-2026-45121 MyBB: Insufficient permission check for calendar select

MyBB is free and open source forum software. Prior to 1.8.40, the calendar module does not check permissions consistently when listing calendars, allowing authenticated users to access titles of calendars that are otherwise inaccessible. The affected calendar-selection paths in calendar.php perfo...

CVE-2026-45121

In MyBB versions before 1.8.40, calendar.php performs permission checks against an invalid calendar context, allowing authenticated users to view titles of otherwise inaccessible calendars. CVSS 3.1 scores this MEDIUM (4.3) with network attack vector and low privileges required. Upgrade to versio...