7.5
CWE
79
Advisory Published
Updated

CVE-2023-46251: Visual editor persistent Cross-site Scripting (XSS) in MyBB

First published: Mon Nov 06 2023(Updated: )

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_.

Credit: security-advisories@github.com

Affected SoftwareAffected VersionHow to fix
Mybb Mybb<1.8.37

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Frequently Asked Questions

  • What is the vulnerability ID for this MyBB vulnerability?

    The vulnerability ID for this MyBB vulnerability is CVE-2023-46251.

  • What is the title of this vulnerability?

    The title of this vulnerability is Visual editor persistent Cross-site Scripting (XSS) in MyBB.

  • What is the affected software version of this vulnerability?

    The affected software version of this vulnerability is MyBB 1.8.37.

  • What is the severity rating of this vulnerability?

    The severity rating of this vulnerability is high (7.5).

  • How can this vulnerability be exploited?

    This vulnerability can be exploited by pointing a victim to a page where the visual editor is active and injecting malicious code.

  • How can I fix this vulnerability in MyBB?

    To fix this vulnerability, update MyBB to version 1.8.37 or a higher version.

  • Where can I find more information about this vulnerability?

    You can find more information about this vulnerability at the following references: [GitHub Advisory](https://github.com/mybb/mybb/security/advisories/GHSA-wj33-q7vj-9fr8) and [MyBB Versions](https://mybb.com/versions/1.8.37/).

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