CVE-2023-46130: Bypassing height value allowed in some theme components

Discourse is an open source platform for community discussion. Prior to version 3.13 of the stable branch and version 3.2.0.beta3 of the beta and tests-passed branches, some theme components allow users to add svgs with unlimited height attributes, and this can affect the availability of subsequent replies in a topic. Most Discourse instances are unaffected, only instances with the svgbob or the mermaid theme component are within scope. The issue is patched in version 3.13 of the stable branch and version 3.2.0.beta3 of the beta and tests-passed branches. As a workaround, disable or remove the relevant theme components.