CVE-2026-45121
Description
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 perform permission checks against an invalid calendar context before returning calendar titles. The uniquely identifying implementation details include titles of inaccessible calendars, and invalid calendar permission context. This issue is fixed in version 1.8.40.
How to fix
Sources list no fixed version or patch link for this vulnerability.
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mybb mybb | < 1.8.40 | — |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.