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.

Affected: npm: fabric

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.

### Deserialization Path (no sanitization)

`loadFromJSON()` (`src/canvas/StaticCanvas.ts:1229`) calls `enlivenObjects()` which calls `_fromObject()` (`src/shapes/Object/Object.ts:1902`). `_fromObject` passes all deserialized properties to the shape constructor via `new this(enlivedObjectOptions)`. The constructor ultimately calls `_setOptions()` (`src/CommonMethods.ts:9`) which iterates over every property and assigns it to the object via `this.set(prop, options[prop])`. There is no allowlist or sanitization - any property in the JSON, including `id`, is set verbatim on the fabric object.

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### Finding 1: XSS via `id` Property Injection

The `id` property from deserialized JSON is interpolated directly into SVG attribute strings without escaping.

**Vulnerable code (`src/shapes/Object/FabricObjectSVGExportMixin.ts`, line 89, `getSvgCommons()`):** ```typescript getSvgCommons( this: FabricObjectSVGExportMixin & FabricObject & { id?: string }, ) { return [ this.id ? `id="${this.id}" ` : '', // <-- unescaped, user-controlled this.clipPath…