Vulnerability Description
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_.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mybb | Mybb | < 1.8.37 |
Related Weaknesses (CWE)
References
- https://github.com/mybb/mybb/commit/6dcaf0b4db6254f1833fe8dae295d9ddc2219276Patch
- https://github.com/mybb/mybb/security/advisories/GHSA-wj33-q7vj-9fr8Vendor Advisory
- https://mybb.com/versions/1.8.37/Release Notes
- https://github.com/mybb/mybb/commit/6dcaf0b4db6254f1833fe8dae295d9ddc2219276Patch
- https://github.com/mybb/mybb/security/advisories/GHSA-wj33-q7vj-9fr8Vendor Advisory
- https://mybb.com/versions/1.8.37/Release Notes
FAQ
What is CVE-2023-46251?
CVE-2023-46251 is a vulnerability with a CVSS score of 7.5 (HIGH). 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....
How severe is CVE-2023-46251?
CVE-2023-46251 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2023-46251?
Check the references section above for vendor advisories and patch information. Affected products include: Mybb Mybb.