CVE-2026-45120
MediumCVSS 5.4Summary
Prior to version 1.8.40, the calendar module in MyBB does not verify private event status consistently, allowing users with viewing and moderation permissions to access and moderate private events. The private-event check used by get_events() in inc/functions_calendar.php and the event action is missing from the remaining calendar.php actions, despite the limited-access behavior described in inc/languages/english/calendar.lang.php. This issue is fixed in version 1.8.40.
Risk Assessment
Users with viewing and moderation permissions may access and manage private events, compromising the confidentiality and integrity of calendar data.
Recommendation
Upgrade MyBB to version 1.8.40 or later to ensure consistent private event checking.
Original NVD description (English source)
MyBB is free and open source forum software. Prior to 1.8.40, the calendar module does not verify private event status consistently, allowing users with viewing and moderation permissions to access and moderate private events. The private-event check used by get_events() in inc/functions_calendar.php and the event action is missing from the remaining calendar.php actions, despite the limited-access behavior described in inc/languages/english/calendar.lang.php. This issue is fixed in version 1.8.40.