Upgrading test Before patch (moodle.git) Create a new Moodle instance WITHOUT this patch. Once done, go to "Site administration -> plugins -> filters -> Mathjax" Check that both MathJax URL setting and the default value point to version 2.7.8. e.g. "https://cdn.jsdelivr.net/npm/mathjax@2.7.8/MathJax.js" After patch (switch to integration.git) Upgrade the site to (integration.git) Check that Filter MathJax have an upgrade to perform. Check that no error appears when the instance is upgrading. Go to "Site administration -> plugins -> filters -> Mathjax" Check that that both MathJax URL setting and the default value now point to version 2.7.9. e.g. "https://cdn.jsdelivr.net/npm/mathjax@2.7.9/MathJax.js" Manual testing 2 Create a regular user and enrol as student in a course Log in as this student. Open the user Edit Profile page. In the Description WYSIWYG, remove any existing content, and paste the following ( use the attached screenshot as a reference just in case:   ):  $$ \unicode {<img src=123 onerror=alert(123)>} $$ $$ x = \frac{\sqrt{144}}{2}\ \times\ (y\ +\ 12) $$ Press "Update profile". Logout and login as admin Go to the user profile. Check that no javascript alert popup appears Check that in the description  appears something like the screenshot  Edit the user profile Check that no javascript alert popup appears Check that the description field looks like the screenshot