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 Import a Theme function. NOTE: the Supplier disputes this because of the allowed actions of Board administrators and because of SSRF mitigation.

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

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.

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

MyBB is a free and open source forum software. The backup management module of the Admin CP may accept .htaccess as the name of the backup file to be deleted, which may expose the stored backup files over HTTP on Apache servers. MyBB 1.8.38 resolves this issue. Users are advised to upgrade. There are no known workarounds for this vulnerability

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['disallowedremoteaddresses']) 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 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: 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.

Cross Site Scripting vulnerability in Mybb Mybb Forums v.1.8.33 allows a local attacker to execute arbitrary code via the theme Name parameter in the theme management component.

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.

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 is a free and open source forum software. The Mail Settings ? Additional Parameters for PHP's mail() function mailparameters 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 ($optionscode; mybbsettings.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.

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'.

Cross Site Scripting (XSS) in MyBB v1.8.20 allows remote attackers to inject arbitrary web script or HTML via the "Title" 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'.

Cross-site Scripting vulnerability in MyBB before 1.8.26 via Custom moderator tools.

SQL Injection vulnerability in MyBB before 1.8.26 via User Groups. (issue 3 of 3).

SQL Injection vulnerability in MyBB before 1.8.26 via the Copy Forum feature in Forum Management. (issue 2 of 3).

SQL Injection vulnerability in MyBB before 1.8.26 via poll vote count. (issue 1 of 3).

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

Cross-site Scripting (XSS) vulnerability in MyBB before 1.8.26 via Nested Auto URL when parsing messages.

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/bbcodessceditor.js file.

Cross-site scripting (XSS) vulnerability in MyBB before 1.6.13 allows remote authenticated users to inject arbitrary web script or HTML via the name parameter in the edit action of the config-profilefields module.

Multiple cross-site scripting (XSS) vulnerabilities in the MyBB (aka MyBulletinBoard) before 1.8.4 allow remote authenticated users to inject arbitrary web script or HTML via the title parameter in the (1) edit or (2) add action in the user-users module or the (3) finduser action or the name parameter in an (4) edit action in the user-user module or the (5) editprofile action to modcp.php.

MyBB before 1.8.22 allows an open redirect on login.