Vulnerabilidades

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_users.buddylist for the target…

### 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](https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N)…

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_resendactivation,…

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 action=recovery_codes page…

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_default in Admin CP,…

MyBB is free and open source forum software. Prior to 1.8.40, the ACP Mass Mail module does not validate certain requests correctly, allowing same-site attackers to create draft entries from archived entries by embedding a specially crafted URL. The Resend route in Admin CP, Users & Groups, Mass Mail, Mass Mailing…

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 requests for the disable…

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 the cansendemail group…

MyBB is free and open source forum software. Prior to 1.8.40, the Mod CP Report Center does not check permissions consistently, allowing moderators without report-management permission to mark reports as resolved. The modcp.php?action=do_reports Mark Selected as Read handler is reachable with canmodcp even without…

MyBB is free and open source forum software. Prior to 1.8.40, the remote requests feature does not correctly handle IPv6 addresses, resulting in a server-side request forgery vulnerability. The default disallowed remote hosts list does not include IPv6 addresses. Verification in fetch_remote_file() fails open when…

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 permission because the…

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…

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.php and the event…

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…

MyBB is free and open source forum software. Prior to 1.8.40, the Contact module does not validate a redirect URL or protocol correctly, resulting in an open redirect and reflected JavaScript code injection. contact.php accepts the redirect target from the from HTTP parameter in $mybb->input['from'] or the Referer…

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. install/index.php processes the…

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…

MyBB is free and open source forum software. Prior to 1.8.40, the Buddy/Ignore component does not sanitize usernames correctly, allowing attackers to perform JavaScript code injection through a specially crafted username. The User CP Buddy/Ignore list and the Select Buddies list in Private Messages pass usernames…

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 profile action to change…

MyBB Last User's Threads in Profile Plugin 1.2 contains a persistent cross-site scripting vulnerability that allows attackers to inject malicious scripts by crafting thread subjects with script tags. Attackers can create threads with script payloads in the subject field that execute when users visit the attacker's…

MyBB My Arcade Plugin 1.3 contains a persistent cross-site scripting vulnerability that allows authenticated users to inject malicious scripts through arcade game score comments. Attackers can add crafted HTML and JavaScript payloads in the comment field that execute when other users view or edit the comment.

MyBB Downloads Plugin 2.0.3 contains a persistent cross-site scripting vulnerability that allows regular members to inject malicious scripts through the download title field. Attackers can submit a new download with HTML/JavaScript code in the title parameter, which executes when administrators validate the download…

MyBB Like Plugin 3.0.0 contains a stored cross-site scripting vulnerability. Authenticated attackers can inject script payloads into post or thread subjects; when other users view a profile that displays the attacker's liked posts, the unsanitized subject is rendered, executing the script in the viewer's browser.

MyBB Delete Account Plugin 1.4 contains a cross-site scripting vulnerability in the account deletion reason input field. Attackers can inject malicious scripts that will execute in the admin interface when viewing delete account reasons.

MyBB Trending Widget Plugin 1.2 contains a cross-site scripting vulnerability that allows attackers to inject malicious scripts through thread titles. Attackers can modify thread titles with script payloads that will execute when other users view the trending widget.