CVE-2026-27013
📋 TL;DR
Fabric.js versions before 7.2.0 have an SVG export vulnerability where user-controlled JSON data isn't properly escaped when converted to SVG. This allows attackers to inject malicious SVG elements with JavaScript event handlers, leading to stored cross-site scripting (XSS). Applications that accept user JSON input via loadFromJSON() and render SVG output are vulnerable.
💻 Affected Systems
- Fabric.js
📦 What is this software?
Fabric.js by Fabricjs
⚠️ Risk & Real-World Impact
Worst Case
Attackers execute arbitrary JavaScript in victims' browsers, potentially stealing session cookies, credentials, or performing actions as the user.
Likely Case
Stored XSS attacks where malicious SVG content is saved and rendered to multiple users, compromising their browser sessions.
If Mitigated
If input validation and output encoding are implemented, impact is limited to SVG rendering issues without code execution.
🎯 Exploit Status
Exploitation requires ability to supply JSON to loadFromJSON() and SVG rendering to victims.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 7.2.0
Vendor Advisory: https://github.com/fabricjs/fabric.js/security/advisories/GHSA-hfvx-25r5-qc3w
Restart Required: No
Instructions:
1. Update Fabric.js to version 7.2.0 or later. 2. Update package.json to specify 'fabric': '^7.2.0'. 3. Run npm update fabric or yarn upgrade fabric. 4. Test SVG export functionality.
🔧 Temporary Workarounds
Input Validation
allValidate and sanitize all JSON input before passing to loadFromJSON()
Output Encoding
allManually escape XML special characters in SVG attributes before toSVG() export
🧯 If You Can't Patch
- Implement strict Content Security Policy (CSP) to block inline scripts
- Disable SVG export functionality for user-generated content
🔍 How to Verify
Check if Vulnerable:
Check if using Fabric.js version <7.2.0 and if application uses loadFromJSON() with user input followed by toSVG() export.Check Version:
npm list fabric | grep fabric or check package.json versionVerify Fix Applied:
Test SVG export with malicious JSON payloads after updating to 7.2.0+📡 Detection & Monitoring
Log Indicators:
- Unusual SVG export requests
- Large or malformed JSON payloads to loadFromJSON endpoints
Network Indicators:
- SVG files containing script tags or event handlers
- JSON payloads with SVG/XML injection patterns
SIEM Query:
source="web_logs" AND (uri="*loadFromJSON*" OR uri="*toSVG*") AND (payload="*onload=*" OR payload="*<script>*")