Description
MyBB is free and open source forum software. Prior to 1.8.40, the calendar module does not validate moderation permissions for the destination calendar when moving events. A user with moderation permission for the source calendar can move an event to a calendar where the user has only viewing permission because the do_move action in calendar.php does not check canmoderateevents for the target calendar. The uniquely identifying implementation details include calendar event move, source calendar moderation permission, and destination calendar viewing permission. This issue is fixed in version 1.8.40.
Published: 2026-08-18
Score: 4.3 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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History

Tue, 18 Aug 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 18 Aug 2026 18:15:00 +0000

Type Values Removed Values Added
First Time appeared Mybb
Mybb mybb
Vendors & Products Mybb
Mybb mybb

Tue, 18 Aug 2026 16:00:00 +0000

Type Values Removed Values Added
Description MyBB is free and open source forum software. Prior to 1.8.40, the calendar module does not validate moderation permissions for the destination calendar when moving events. A user with moderation permission for the source calendar can move an event to a calendar where the user has only viewing permission because the do_move action in calendar.php does not check canmoderateevents for the target calendar. The uniquely identifying implementation details include calendar event move, source calendar moderation permission, and destination calendar viewing permission. This issue is fixed in version 1.8.40.
Title MyBB: Insufficient permission check for calendar event move
Weaknesses CWE-863
References
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-18T17:54:36.990Z

Reserved: 2026-05-08T20:08:17.208Z

Link: CVE-2026-45122

cve-icon Vulnrichment

Updated: 2026-08-18T17:54:28.229Z

cve-icon NVD

Status : Received

Published: 2026-08-18T16:17:07.243

Modified: 2026-08-18T18:17:35.967

Link: CVE-2026-45122

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-18T18:00:04Z

Weaknesses