CVE-2026-3748
📋 TL;DR
CVE-2026-3748 is an unrestricted file upload vulnerability in Bytedesk's SVG file handler that allows attackers to upload malicious files without proper validation. This affects Bytedesk versions up to 1.3.9 and can be exploited remotely. Attackers could potentially upload malicious SVG files containing scripts or other dangerous content.
💻 Affected Systems
- Bytedesk
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution or complete system compromise through malicious file upload leading to server-side attacks
Likely Case
File upload leading to stored XSS, defacement, or malware distribution through uploaded content
If Mitigated
Limited impact with proper file validation and upload restrictions in place
🎯 Exploit Status
Exploit has been released to the public and remote exploitation is possible
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.4.5.1
Vendor Advisory: https://github.com/Bytedesk/bytedesk/commit/975e39e4dd527596987559f56c5f9f973f64eff7
Restart Required: Yes
Instructions:
1. Backup current installation. 2. Upgrade Bytedesk to version 1.4.5.1 or later. 3. Restart the application/service. 4. Verify the patch is applied by checking the commit hash includes 975e39e4dd527596987559f56c5f9f973f64eff7.
🔧 Temporary Workarounds
Disable SVG uploads
allTemporarily disable SVG file upload functionality in the application configuration
Modify application configuration to reject SVG file uploads
Implement file validation
allAdd server-side file type validation and content inspection for uploaded files
Implement file signature validation and restrict allowed file types
🧯 If You Can't Patch
- Implement WAF rules to block malicious file uploads targeting the upload endpoint
- Restrict network access to the upload functionality and implement strict file size limits
🔍 How to Verify
Check if Vulnerable:
Check Bytedesk version. If version is 1.3.9 or earlier, the system is vulnerable.Check Version:
Check application version in admin panel or configuration filesVerify Fix Applied:
Verify Bytedesk version is 1.4.5.1 or later and check that commit 975e39e4dd527596987559f56c5f9f973f64eff7 is present in the codebase.📡 Detection & Monitoring
Log Indicators:
- Unusual file upload patterns
- Multiple SVG file upload attempts
- Large file uploads to upload endpoint
Network Indicators:
- POST requests to /upload endpoints with SVG content
- Unusual traffic patterns to file upload functionality
SIEM Query:
source="web_server" AND (uri_path="/upload" OR uri_path LIKE "%/upload%") AND (file_extension="svg" OR content_type="image/svg+xml")🔗 References
- https://github.com/Bytedesk/bytedesk/
- https://github.com/Bytedesk/bytedesk/commit/975e39e4dd527596987559f56c5f9f973f64eff7
- https://github.com/Bytedesk/bytedesk/issues/18
- https://github.com/Bytedesk/bytedesk/issues/18#issue-3993448721
- https://github.com/Bytedesk/bytedesk/issues/18#issuecomment-3976672973
- https://github.com/Bytedesk/bytedesk/releases/tag/v1.4.5.1
- https://vuldb.com/?ctiid.349726
- https://vuldb.com/?id.349726
- https://vuldb.com/?submit.768028
