MyBB is free and open source forum software. Prior to 1.8.40, the Admin CP UTF-8 Conversion module does not validate certain requests correctly, allowing same-site attackers to alter table encoding and deny service with a specially crafted URL. The do=all control flow in admin/modules/tools/system_health.php performs ALTER TABLE operations, column rewrite phases, and fulltext index rebuilds on GET requests for the database table named by the table parameter without request verification. The uniquely identifying implementation details include GET requests without request verification. This issue is fixed in version 1.8.40.

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Tue, 18 Aug 2026 17:45:00 +0000

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

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Description MyBB is free and open source forum software. Prior to 1.8.40, the Admin CP UTF-8 Conversion module does not validate certain requests correctly, allowing same-site attackers to alter table encoding and deny service with a specially crafted URL. The do=all control flow in admin/modules/tools/system_health.php performs ALTER TABLE operations, column rewrite phases, and fulltext index rebuilds on GET requests for the database table named by the table parameter without request verification. The uniquely identifying implementation details include GET requests without request verification. This issue is fixed in version 1.8.40.
Title MyBB: ACP UTF-8 Conversion CSRF
Weaknesses CWE-352
References
Metrics cvssV3_1

{'score': 4.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-18T15:49:14.763Z

Reserved: 2026-05-08T20:08:17.207Z

Link: CVE-2026-45119

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-18T16:17:06.773

Modified: 2026-08-18T16:17:06.773

Link: CVE-2026-45119

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-18T18:45:03Z

Weaknesses