Vulnerabilities

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 profile page.

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 in downloads.php.

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.

MyBB Thread Redirect Plugin 0.2.1 contains a cross-site scripting vulnerability in the custom text input field for thread redirects. Attackers can inject malicious SVG scripts that will execute when other users view the thread, allowing arbitrary script execution.

MyBB 1.8.32 contains a chained vulnerability that allows authenticated administrators to bypass avatar upload restrictions and execute arbitrary code. Attackers can modify upload path settings, upload a malicious PHP-embedded image file, and execute commands through the language configuration editing interface.

MyBB is free and open source forum software. Prior to version 1.8.39, the upgrade component does not validate user input properly, which allows attackers to perform local file inclusion (LFI) via a specially crafted parameter value. In order to exploit the vulnerability, the installer must be unlocked (no `install/lock` file present) and the upgrade script must be accessible (by re-installing the forum via access to `install/index.php`; when the forum has not yet been installed; or the attacker is authenticated as a forum administrator). MyBB 1.8.39 resolves this issue.

An issue in MyBB 1.8.38 allows a remote attacker to obtain sensitive information via the Mail function. NOTE: the Supplier disputes this because of the allowed actions of Board administrators and because of SSRF mitigation.

A stored cross-site scripting (XSS) vulnerability in the component install\index.php of MyBB v1.8.38 allows attackers to execute arbitrary web scripts or HTML via a crafted payload injected into the Website Name parameter. NOTE: this is disputed by the Supplier because Website Name can only be set by an administrator, who may use JavaScript if they wish.

MyBB is a free and open source forum software. The default list of disallowed remote hosts does not contain the `127.0.0.0/8` block, which may result in a Server-Side Request Forgery (SSRF) vulnerability. The Configuration File's _Disallowed Remote Addresses_ list (`$config['disallowed_remote_addresses']`) contains the address `127.0.0.1`, but does not include the complete block `127.0.0.0/8`. MyBB 1.8.38 resolves this issue in default installations. Administrators of installed boards should update the existing configuration (`inc/config.php`) to include all addresses blocked by default. Additionally, users are advised to verify that it includes any other IPv4 addresses resolving to the server and other internal resources. Users unable to upgrade may manually add 127.0.0.0/8' to their disallowed address list.

MyBB is a free and open source forum software. Custom MyCode (BBCode) for the visual editor (_SCEditor_) doesn't escape input properly when rendering HTML, resulting in a DOM-based XSS vulnerability. This weakness can be exploited by pointing a victim to a page where the visual editor is active (e.g. as a post or Private Message) and operates on a maliciously crafted MyCode message. This may occur on pages where message content is pre-filled using a GET/POST parameter, or on reply pages where a previously saved malicious message is quoted. The impact is be mitigated when: 1. the visual editor is disabled globally (_Admin CP → Configuration → Settings → Clickable Smilies and BB Code: [Clickable MyCode Editor](https://github.com/mybb/mybb/blob/mybb_1836/install/resources/settings.xml#L2087-L2094)_ is set to _Off_), or 2. the visual editor is disabled for individual user accounts (_User CP → Your Profile → Edit Options_: _Show the MyCode formatting options on the posting pages_ checkbox is not checked). MyBB 1.8.37 resolves this issue with the commit `6dcaf0b4d`. Users are advised to upgrade. Users unable to upgrade may mitigate the impact without upgrading MyBB by changing the following setting (_Admin CP → Configuration → Settings_): - _Clickable Smilies and BB Code → [Clickable MyCode Editor](https://github.com/mybb/mybb/blob/mybb_1836/install/resources/settings.xml#L2087-L2094)_: _Off_. Similarly, individual MyBB forum users are able to disable the visual editor by diabling the account option (_User CP → Your Profile → Edit Options_) _Show the MyCode formatting options on the posting pages_.

Installer RCE on settings file write in MyBB before 1.8.22.

MyBB before 1.8.36 allows Code Injection by users with certain high privileges. Templates in Admin CP intentionally use eval, and there was some validation of the input to eval, but type juggling interfered with this when using PCRE within PHP.

In MyBB before 1.8.34, there is XSS in the User CP module via the user email field.

In the Active Threads Plugin 1.3.0 for MyBB, the activethreads.php date parameter is vulnerable to XSS when setting a time period.

MyBB before 1.8.33 allows Directory Traversal. The Admin CP Languages module allows remote authenticated users, with high privileges, to achieve local file inclusion and execution.

MyBB 1.8.31 has a Cross-site scripting (XSS) vulnerability in the visual MyCode editor (SCEditor) allows remote attackers to inject HTML via user input or stored data

MyBB is a free and open source forum software. The _Mail Settings_ → Additional Parameters for PHP's mail() function mail_parameters setting value, in connection with the configured mail program's options and behavior, may allow access to sensitive information and Remote Code Execution (RCE). The vulnerable module requires Admin CP access with the `_Can manage settings?_` permission and may depend on configured file permissions. MyBB 1.8.31 resolves this issue with the commit `0cd318136a`. Users are advised to upgrade. There are no known workarounds for this vulnerability.

MyBB is a free and open source forum software. In affected versions the Admin CP's Settings management module does not validate setting types correctly on insertion and update, making it possible to add settings of supported type `php` with PHP code, executed on on _Change Settings_ pages. This results in a Remote Code Execution (RCE) vulnerability. The vulnerable module requires Admin CP access with the `Can manage settings?` permission. MyBB's Settings module, which allows administrators to add, edit, and delete non-default settings, stores setting data in an options code string ($options_code; mybb_settings.optionscode database column) that identifies the setting type and its options, separated by a new line character (\n). In MyBB 1.2.0, support for setting type php was added, for which the remaining part of the options code is PHP code executed on Change Settings pages (reserved for plugins and internal use). MyBB 1.8.30 resolves this issue. There are no known workarounds.

MyBB before 1.8.29 allows Remote Code Injection by an admin with the "Can manage settings?" permission. The Admin CP's Settings management module does not validate setting types correctly on insertion and update, making it possible to add settings of supported type "php" with PHP code, executed on Change Settings pages.

MyBB before 1.8.28 allows stored XSS because the displayed Template Name value in the Admin CP's theme management is not escaped properly.

The MyBB Cross-Poster WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient input validation and sanitization via several parameters found in the ~/classes/MyBBXPSettings.php file which allowed attackers with administrative user access to inject arbitrary web scripts, in versions up to and including 1.0. This affects multi-site installations where unfiltered_html is disabled for administrators, and sites where unfiltered_html is disabled.

Cross Site Scripting (XSS) in MyBB v1.8.20 allows remote attackers to inject arbitrary web script or HTML via the "Description" field found in the "Add New Forum" page by doing an authenticated POST HTTP request to '/Upload/admin/index.php?module=forum-management&action=add'.

SQL Injection vulnerablity in MyBB before 1.8.26 via theme properties included in theme XML files.

MyBB before 1.8.25 allows stored XSS via nested [email] tags with MyCode (aka BBCode).

In MyBB before version 1.8.24, the custom MyCode (BBCode) for the visual editor doesn't escape input properly when rendering HTML, resulting in a DOM-based XSS vulnerability. The weakness can be exploited by pointing a victim to a page where the visual editor is active (e.g. as a post or Private Message) and operates on a maliciously crafted MyCode message. This may occur on pages where message content is pre-filled using a GET/POST parameter, or on reply pages where a previously saved malicious message is quoted. After upgrading MyBB to 1.8.24, make sure to update the version attribute in the `codebuttons` template for non-default themes to serve the latest version of the patched `jscripts/bbcodes_sceditor.js` file.

MyBB before 1.8.22 allows an open redirect on login.

An CSRF issue was discovered in the JN-Jones MyBB-2FA plugin through 2014-11-05 for MyBB. An attacker can forge a request to an installed mybb2fa plugin to control its state via usercp.php?action=mybb2fa&do=deactivate (or usercp.php?action=mybb2fa&do=activate). A deactivate operation lowers the security of the targeted account by disabling two factor authentication.

In MyBB before 1.8.21, an attacker can exploit a parsing flaw in the Private Message / Post renderer that leads to [video] BBCode persistent XSS to take over any forum account, aka a nested video MyCode issue.

MyBB 1.8.19 allows remote attackers to obtain sensitive information because it discloses the username upon receiving a password-reset request that lacks the code parameter.