CVE-2026-45120

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.

Published 18 Aug 2026, 16:17 UTC Last modified 18 Aug 2026, 16:17 UTC

5.4

CVSS 3.1 MEDIUM base score CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Attack profile

The conditions required to exploit this vulnerability and its potential impact.

Attack vector Network

Attack complexity Low

Privileges required Low

User interaction None

Scope Unchanged

Confidentiality Low

Integrity Low

Availability None

Exploitability2.8

Impact2.5

Affected products

Product applicability statements supplied with the NVD record.

NVD has not published structured affected-product data for this record.

Weakness classification

CWE categories help security teams group the underlying software weakness.

CWECWE-639

Source references

External advisories, patches and technical reports attached to this CVE record.

NVD National Vulnerability Database recordnvd.nist.gov 01 Technical reference security-advisories@github.com 02 Technical reference security-advisories@github.com 03 Technical reference security-advisories@github.com 04 Technical reference security-advisories@github.com