MyBB: Insufficient permission check for calendar event move

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-45122
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-18 16:17:07 UTC
Updated2026-08-18 18:17:35 UTC
DescriptionMyBB 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.

Risk And Classification

Primary CVSS: v3.1 4.3 MEDIUM from [email protected]

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

Problem Types: CWE-863 | CWE-863 CWE-863: Incorrect Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
3.1CNADECLARED4.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mybb Mybb affected < 1.8.40 Not specified

References

ReferenceSourceLinkTags
github.com/mybb/mybb/commit/86ed2058e7f9a2c14828e731f684e997f9bb220c [email protected] github.com
github.com/mybb/mybb/releases/tag/mybb_1840 [email protected] github.com
mybb.com/versions/1.8.40 [email protected] mybb.com
github.com/mybb/mybb/security/advisories/GHSA-839m-gpw8-59j4 [email protected] github.com
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