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OpenAdvisories
Medium · 5.4 CVE-2026-45120 EUVD-2026-61017

MyBB: Insufficient authorization for private calendar events

Published Aug 18, 2026 · Updated Aug 18, 2026 · Assigned by GitHub_M

Description

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.

Affected products

VendorProductAffectedFixed
mybb mybb < 1.8.40 —

References