Provide references for CVE-2021-39338.
Where can I find more information about CVE-2021-39338?
References are available at: https://www.wordfence.com/vulnerability-advisories/#CVE-2021-39338, https://github.com/BigTiger2020/word-press/blob/main/MyBB%20Cross-Poster.md, https://plugins.trac.wordpress.org/browser/mybb-cross-poster/trunk/classes/MyBBXPSettings.php.