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CVE-2026-45116 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 user datahandler does not properly validate checkbox and multiselect profile field types, resulting in stored JavaScript code injection. UserDataHandler::verify_profile_fields() only performs the specialized validation when is_array($profile_fields[$field]) is true. A non-array profile_fields[fidX] value instead of the expected profile_fields[fidX][] shape falls through to generic text handling and is stored without verification. The affected value is then rendered directly by member.php and inc/functions_post.php rather than processed by the MyCode parser. The uniquely identifying implementation details include inc/datahandlers/user.php. 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:8.7 HIGHVector:CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://github.com/mybb/mybb/commit/c32f0c22baab704a68b8d58fcdd2f26fadbbe19b	[email protected]
https://github.com/mybb/mybb/releases/tag/mybb_1840	[email protected]
https://github.com/mybb/mybb/security/advisories/GHSA-4p6g-p3qh-559v	[email protected]
https://mybb.com/versions/1.8.40	[email protected]

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-79	Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')	[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]