{"id":"GHSA-hfvx-25r5-qc3w","summary":"Fabric.js Affected by Stored XSS via SVG Export","details":"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.\n\n### Deserialization Path (no sanitization)\n\n`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.\n\n---\n\n### Finding 1: XSS via `id` Property Injection \n\nThe `id` property from deserialized JSON is interpolated directly into SVG attribute strings without escaping.\n\n**Vulnerable code (`src/shapes/Object/FabricObjectSVGExportMixin.ts`, line 89, `getSvgCommons()`):**\n```typescript\ngetSvgCommons(\n  this: FabricObjectSVGExportMixin & FabricObject & { id?: string },\n) {\n  return [\n    this.id ? `id=\"${this.id}\" ` : '',  // \u003c-- unescaped, user-controlled\n    this.clipPath\n      ? `clip-path=\"url(#${...})\" `\n      : '',\n  ].join('');\n}\n```\n\nThis method is called in `_createBaseSVGMarkup()` (same file, line 178) which wraps every object's SVG output in a `\u003cg\u003e` element. Every fabric object type (Rect, Circle, Path, Text, Image, Group, etc.) inherits this mixin, so the `id` injection vector applies to all object types.\n\n**Contrast with text content, which IS escaped:**\n```typescript\n// src/shapes/Text/TextSVGExportMixin.ts:186\nreturn `\u003ctspan ...\u003e${escapeXml(char)}\u003c/tspan\u003e`;\n```\n\nThe inconsistency shows that the intention was to prevent injection but was missed w attribute contexts.\n\n---\n\n### Finding 2: XSS via Image `src` / `xlink:href` Injection \n\nImage source URLs are interpolated raw into `xlink:href` in `_toSVG()`.\n\n**Vulnerable code (`src/shapes/Image.ts`, line 404, `_toSVG()`):**\n```typescript\nimageMarkup.push(\n  '\\t\u003cimage ',\n  'COMMON_PARTS',\n  `xlink:href=\"${this.getSvgSrc(true)}\" x=\"${x - this.cropX}\" y=\"${\n    y - this.cropY\n  }\" ...`  // \u003c-- unescaped\n);\n```\n\n`getSvgSrc()` returns the image `src` property which is set from JSON during deserialization. An attacker can inject a `src` value that breaks out of the `xlink:href` attribute.\n\n---\n\n### Finding 3: XSS via Pattern `sourceToString()` \n\n**Vulnerable code (`src/Pattern/Pattern.ts`, line 181, `toSVG()`):**\n```typescript\n`\u003cimage x=\"0\" y=\"0\" ... xlink:href=\"${this.sourceToString()}\"\u003e\u003c/image\u003e`\n// \u003c-- unescaped, returns this.source.src for image sources\n```\n\nAdditionally, Pattern's constructor (`line 92–94`) runs `this.id = uid()` *before* `Object.assign(this, options)`, meaning a user-supplied `id` in the pattern JSON overwrites the auto-generated uid. The pattern `id` is then interpolated unescaped on line 180:\n```typescript\n`\u003cpattern id=\"SVGID_${id}\" x=\"${patternOffsetX}\" ...\u003e`\n```\n\n---\n\n### Finding 4: Gradient `id` Partial Injection (lower Severity)\n\n**Vulnerable code (`src/gradient/Gradient.ts`, line 212, `toSVG()`):**\n```typescript\n`id=\"SVGID_${this.id}\"`  // \u003c-- unescaped\n```\n\nGradient's constructor (`line 125`) computes `id: id ? `${id}_${uid()}` : uid()`. If a user-supplied `id` is present in the gradient JSON, it is prepended to the auto-generated uid. The user-controlled portion is interpolated unescaped into the SVG. This is exploitable but the payload is constrained by the `_\u003cuid\u003e` suffix appended after it.\n\n---\n\n## Impact\n\nAny application that:\n1. Accepts user-supplied JSON (via `loadFromJSON()`, collaborative sharing, import features, CMS plugins), AND\n2. Renders the `toSVG()` output in a browser context (SVG preview, export download rendered in-page, email template, embed)\n\n...is vulnerable to stored XSS. An attacker can execute arbitrary JavaScript in the victim's browser session.\n\nReal-world attack scenarios:\n- Collaborative design tools (Canva-like apps) where users share canvas state as JSON\n- CMS or e-commerce platforms with fabric.js-based editors that store/render designs\n- Any export-to-SVG workflow where the SVG is later displayed in a browser\n\n---\n\n## Remediation\n\nUpdate to [fabric.js 7.2.0](https://github.com/fabricjs/fabric.js/releases/tag/v720) or newer version. \n\n---\n\n## Confirmed Affected Files\n\n| File | Issue | Method | Exploitable |\n|---|---|---|---|\n| `src/shapes/Object/FabricObjectSVGExportMixin.ts` | Unescaped `this.id` in attribute | `getSvgCommons()` | Yes - primary vector, all object types |\n| `src/shapes/Image.ts` | Unescaped `getSvgSrc()` in `xlink:href` | `_toSVG()` | Yes |\n| `src/Pattern/Pattern.ts` | Unescaped `sourceToString()` in `xlink:href`; unescaped `id` in attribute | `toSVG()` | Yes |\n| `src/gradient/Gradient.ts` | User-supplied `id` prefix interpolated unescaped | `toSVG()` | Yes (partial - uid suffix appended) |","aliases":["CVE-2026-27013"],"modified":"2026-02-22T23:24:35.168357Z","published":"2026-02-18T22:44:58Z","database_specific":{"cwe_ids":["CWE-116","CWE-79"],"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-02-18T22:44:58Z","nvd_published_at":"2026-02-19T20:25:44Z"},"references":[{"type":"WEB","url":"https://github.com/fabricjs/fabric.js/security/advisories/GHSA-hfvx-25r5-qc3w"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27013"},{"type":"WEB","url":"https://github.com/fabricjs/fabric.js/commit/7e1a122defd8feefe4eb7eaf0c180d7b0aeb6fee"},{"type":"PACKAGE","url":"https://github.com/fabricjs/fabric.js"},{"type":"WEB","url":"https://github.com/fabricjs/fabric.js/releases/tag/v720"}],"affected":[{"package":{"name":"fabric","ecosystem":"npm","purl":"pkg:npm/fabric"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"7.2.0"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-hfvx-25r5-qc3w/GHSA-hfvx-25r5-qc3w.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:L"}]}