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CVE-2026-45121 Details

UNDERGOING ENRICHMENT

The CVE is currently being enriched by the Volerion team. The enrichment process results in the association of reference link tags, CVSS, and CPE applicability statement data.

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.

Metrics

CVSS 3.x Severity and Vector Strings:

VolerionCVSS-B:…Vector:This vulnerability is currently being analyzed.

CNA: [email protected]CVSS-B:4.3 MEDIUMVector:CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://github.com/mybb/mybb/commit/78e07fea34a6f6c326e668526bfb8e451c19e966	[email protected]
https://github.com/mybb/mybb/releases/tag/mybb_1840	[email protected]
https://github.com/mybb/mybb/security/advisories/GHSA-r25v-7pcm-q34p	[email protected]
https://mybb.com/versions/1.8.40	[email protected]

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-863	Incorrect Authorization	[email protected]

Affected Products

This vulnerability is currently being analyzed

Change History

2 change records found show changes

Date	Action	Recorded By
Aug 18, 2026	CVE Modified	CISA-ADP
Aug 18, 2026	New CVE Received	[email protected]