SVGO: removeScripts incompletely sanitizes executable HTML in SVG foreignObject elements

SVGO, short for SVG Optimizer, is a Node.js library and command-line application for optimizing SVG files. From version 1.0.0 until versions 2.8.4, 3.3.5, and 4.1.0, the opt-in removeScripts plugin, named removeScriptElement in versions 2 and 3 and implemented in plugins/removeScripts.js, removes SVG and XHTML script elements but does not inspect executable HTML content inside SVG foreignObject elements. Event-handler attributes such as onload and onbeforetoggle, srcdoc documents, and executable URLs in the action, data, formaction, href, and src attributes can remain in attacker-controlled SVG input. When an application uses the plugin as its only protection and serves the optimized SVG in an active browser context, the payload can execute script in the viewer's origin, expose data, modify content, or perform actions as the victim. This issue is fixed in versions 2.8.4, 3.3.5, and 4.1.0.