Fabric.js Affected by Stored XSS via SVG Export

Summary

Fabric.js is a Javascript HTML5 canvas library. Prior to version 7.2.0, Fabric.js applies `escapeXml()` to text content during SVG export (`src/shapes/Text/TextSVGExportMixin.ts:186`) but fails to apply it to other user-controlled string values that are interpolated into SVG attribute markup. When attacker-controlled JSON is loaded via `loadFromJSON()` and later exported via `toSVG()`, the unescaped values break out of XML attributes and inject arbitrary SVG elements including event handlers. Any application that accepts user-supplied JSON (via `loadFromJSON()`, collaborative sharing, import features, CMS plugins) and renders the `toSVG()` output in a browser context (SVG preview, export download rendered in-page, email template, embed) is vulnerable to stored XSS. An attacker can execute arbitrary JavaScript in the victim's browser session. Version 7.2.0 contains a fix.