PT-2026-77185

MyBB is free and open source forum software. Prior to 1.8.40, the User CP Buddy/Ignore List component does not validate reciprocal buddy-list updates correctly. The usercp.php?action=do editlists delete handler removes the selected entry from the acting user's list and then updates mybb...

PT-2026-77182

MyBB is free and open source forum software. Prior to 1.8.40, the Admin CP Recovery Codes module does not validate requests correctly, allowing same-site attackers to rotate a victim administrator's recovery codes with a specially crafted URL. The Admin CP Home, Preferences, Recovery Codes...

PT-2026-77170

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...

PT-2026-77176

MyBB 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...

PT-2026-77180

MyBB is free and open source forum software. Prior to 1.8.40, the Admin CP Security Questions module does not validate the anti-CSRF token correctly, allowing same-site attackers to enable or disable registration challenge questions with a specially crafted URL. The controller processes GET...

PT-2026-77179

MyBB is free and open source forum software. Prior to 1.8.40, the Email User controller does not sanitize sender names correctly, resulting in mail header injection. member.php?action=do emailuser accepts the fromname HTTP parameter for guests or the stored username for authenticated users when t...

PT-2026-77183

MyBB is free and open source forum software. Prior to 1.8.40, the built-in CAPTCHA does not consistently enforce single-use semantics, allowing remote attackers to bypass CAPTCHA controls through challenge replay. The successful validation paths in contact.php, member.php?action=do...

PT-2026-77173

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/syste...

PT-2026-77184

Impact The registration component does not validate the text-based Security Question CAPTCHA correctly, allowing attackers to bypass the challenge via a specially crafted value. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Details The public Registration workflow member.php?action=do register...

PT-2026-77174

MyBB is free and open source forum software. Prior to 1.8.40, the calendar module does not verify private event status consistently, allowing users with viewing and moderation permissions to access and moderate private events. The private-event check used by get events in inc/functions calendar.p...

PT-2026-77171

MyBB is free and open source forum software. From 1.8.13 until 1.8.40, the installer module does not properly escape user-supplied database configuration values written to the configuration file, resulting in PHP code injection and remote code execution when the installer is available...

PT-2026-77181

MyBB is free and open source forum software. Prior to 1.8.40, the ACP Users View Manager module does not validate requests correctly, allowing same-site attackers to change a victim administrator's default user list view by embedding a specially crafted URL. The Set as Default control named set...

CVE-2026-58054

Rejected reason: This CVE ID has been rejected or withdrawn by its CVE Numbering Authority. This CVE was assigned on the basis that the permission system allows a limited administrator to grant privileges exceeding their own authorization scope, potentially constituting an insecure default...

CVE-2026-58054

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CVE-2026-58054

CVE-2026-58054 is not a public vulnerability in practice; however, connected details describe a concrete issue in MyBB 1.8.40 where a limited ACP user can assign the Administrators (gid 4) group because verify_usergroup() unconditionally returns true for that group. This enables privilege escalat...

CVE-2026-58054

This CVE ID has been rejected or withdrawn by its CVE Numbering Authority. This CVE was assigned on the basis that the permission system allows a limited administrator to grant privileges exceeding their own authorization scope, potentially constituting an insecure default configuration. Followin...

CVE-2026-58054

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EUVD-2026-39974

MyBB 1.8.40 does not restrict which usergroup a limited Admin Control Panel user may assign when creating or editing users; the user module offers the Administrators group gid 4 and its datahandler's verifyusergroup unconditionally returns true. An admin holding only the delegated user-management...

PT-2026-53086

Name of the Vulnerable Software and Affected Versions MyBB version 1.8.40 Description An issue exists where users with limited Admin Control Panel ACP access can assign any usergroup to an account during creation or editing. This occurs because the verify usergroup function in the user module...

CVE-2021-47934 MyBB Timeline Plugin 1.0 Cross-Site Scripting and CSRF

MyBB Timeline Plugin 1.0 contains cross-site scripting vulnerabilities that allow attackers to inject malicious scripts through thread titles, post content, and user profile fields like Location and Bio. Attackers can also exploit a cross-site request forgery vulnerability in the timeline.php...