CVE-2026-45119
Published:August 18, 2026
Updated:September 23, 2026
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.
Affected Packages
https://github.com/mybb/mybb.git (GITHUB):
Affected version(s) >=mybb_1800 <mybb_1840Fix Suggestion:
Update to version mybb_1840Related Resources (6)
Do you need more information?
Contact UsCVSS v4
Base Score:
5.1
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
PASSIVE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
LOW
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
4.6
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
LOW
Weakness Type (CWE)
Cross-Site Request Forgery (CSRF)
EPSS
Base Score:
0.13