GHSA-2p49-hgcm-8545: SVGO removeScripts plugin leaves some executable scripts intact

Summary SVGO's removeScripts plugin (disabled by default) removes scripts from the SVG, however executable scripts were left intact in some cases. If a consumer relied on this plugin for sanitization and served them to users, these SVGs could open up doors to XSS. Details SVGO has a plugin for removing scripts from an SVG, which removes: - <script> elements - JavaScript URIs (v4 and v3 only) - on… event handlers (v4 and v3 only) While SVGO is not a sanitization library, SVGO continues to maintain the plugin for those already using it for this purpose. However, there were two problems: - SVGO did not check namespaced/prefixed script elements, for example if one declared an explicit prefix for the SVG namespace ( <svg:script>) instead of using the default namespace ( <script>), the <svg:script> tag would be left intact. - SVGO case sensitively matched JavaScript URIs, but it should've been case-insensitive. Proof of Concept import { optimize } from 'svgo'; /** Presume that this string was obtained in some other way, such as network. */ const original = ` <svg xmlns="http://www.w3.org/2000/svg" xmlns:svg="http://www.w3.org/2000/svg" xmlns:uwu="http://www.w3.org/1999/xlink" viewBox="0 0 100 100" version="1.1"> <a uwu:href="JavaScript:(() =&gt; { alert(document.cookie) })();"><text y="30">uwu</text></a> <svg:script> alert(document.cookie); </svg:script> </svg> `; optimize(original, { plugins: ['removeScripts'] }); // Did not remove <svg:script> or uwu:href="JavaScript:…—still executed by browsers. Impact If you run SVGO on untrusted input (e.g., user uploads to a web application) and you depended on removeScripts, then some scripts may still be present. If that SVG was then opened directly by another user on the same domain, it could invoke scripts that could read local storage or cookies. This may affect you if you have enabled one of the following: | SVGO Version | Plugin Name | |---|---| | v4 | removeScripts | | v3 | removeScriptElement | | v2 | removeS