CVE-2025-56515
📋 TL;DR
This CVE describes a cross-site scripting (XSS) vulnerability in Fiora chat application versions 1.0.0 through user avatar upload functionality. Attackers can upload malicious SVG files containing JavaScript that executes when viewed, allowing session hijacking, cookie theft, and unauthorized actions. All users of affected Fiora versions who view compromised profiles are at risk.
💻 Affected Systems
- Fiora chat application
📦 What is this software?
Fiora by Suisuijiang
⚠️ Risk & Real-World Impact
Worst Case
Complete account takeover, data exfiltration, and lateral movement through the chat platform leading to organizational compromise.
Likely Case
Session hijacking of users viewing malicious profiles, cookie theft, and unauthorized actions within compromised user contexts.
If Mitigated
Limited impact with proper content security policies and file validation, potentially blocking malicious SVG rendering.
🎯 Exploit Status
Exploitation requires user account access to upload avatar, but public proof-of-concept exists in GitHub repository.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not specified
Vendor Advisory: Not available
Restart Required: No
Instructions:
Check GitHub repository for updates, implement SVG content validation, sanitize user-uploaded files, and apply content security policies.
🔧 Temporary Workarounds
Disable SVG uploads
allConfigure application to reject SVG files entirely from avatar uploads
Modify file upload validation to block .svg extensions
Implement Content Security Policy
allAdd CSP headers to prevent inline script execution from SVG files
Add 'Content-Security-Policy: script-src 'self'' header
🧯 If You Can't Patch
- Implement web application firewall (WAF) rules to block malicious SVG uploads
- Disable avatar upload functionality entirely in application configuration
🔍 How to Verify
Check if Vulnerable:
Attempt to upload SVG file containing <foreignObject><iframe> or JavaScript event handlers; check if file is accepted and rendered without sanitization.Check Version:
Check package.json or application version endpoint if availableVerify Fix Applied:
Test SVG upload with malicious content; verify file is rejected or sanitized, and JavaScript does not execute when rendered.📡 Detection & Monitoring
Log Indicators:
- Unusual SVG file uploads
- Multiple failed upload attempts with SVG files
- Large SVG files containing script-like content
Network Indicators:
- HTTP POST requests with SVG content to avatar upload endpoints
- Unusual file size patterns for avatar images
SIEM Query:
source="web_server" AND (uri_path="/upload/avatar" OR uri_path="/api/avatar") AND file_extension="svg"