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

Visual editor persistent Cross-site Scripting (XSS) in MyBB

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_.

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.

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.

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 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).

Installer RCE on settings file write in MyBB before 1.8.22.

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'.

XSS in MyBB

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.

In MyBB before 1.8.21, an attacker can abuse a default behavior of MySQL on many systems (that leads to truncation of strings that are too long for a database column) to create a PHP shell in the cache directory of a targeted forum via a crafted XML import, as demonstrated by truncation of aaaaaaaaaaaaaaaaaaaaaaaaaa.php.css to aaaaaaaaaaaaaaaaaaaaaaaaaa.php with a 30-character limit, aka theme import stylesheet name RCE.

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.