CVE-2026-27944
📋 TL;DR
Nginx UI versions before 2.3.3 expose an unauthenticated API endpoint that discloses encryption keys in response headers, allowing attackers to download and decrypt full system backups containing sensitive credentials, SSL keys, and configurations. This affects all deployments using vulnerable Nginx UI versions. The vulnerability requires no authentication and provides immediate access to critical system data.
💻 Affected Systems
- Nginx UI
⚠️ 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
Complete system compromise: attackers obtain all credentials, SSL private keys, session tokens, and configurations, enabling lateral movement, data theft, and persistent access to the entire infrastructure.
Likely Case
Sensitive data exfiltration including user credentials, SSL certificates, and Nginx configurations, leading to credential reuse attacks, man-in-the-middle attacks, and service disruption.
If Mitigated
Limited impact if network segmentation prevents external access to the Nginx UI management interface, though internal threats remain.
🎯 Exploit Status
Exploitation requires only HTTP requests to the vulnerable endpoint. The GitHub advisory includes technical details that facilitate easy weaponization.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.3.3
Vendor Advisory: https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-g9w5-qffc-6762
Restart Required: Yes
Instructions:
1. Stop Nginx UI service. 2. Backup current configuration. 3. Update to version 2.3.3 or later. 4. Restart Nginx UI service. 5. Verify the /api/backup endpoint now requires authentication.
🔧 Temporary Workarounds
Network Access Restriction
linuxBlock external and unnecessary internal access to Nginx UI management interface
iptables -A INPUT -p tcp --dport <nginx-ui-port> -s <trusted-ips> -j ACCEPT
iptables -A INPUT -p tcp --dport <nginx-ui-port> -j DROP
Reverse Proxy Authentication
allPlace Nginx UI behind a reverse proxy with authentication
# Configure nginx/apache with basic auth or other authentication method
🧯 If You Can't Patch
- Immediately restrict network access to Nginx UI interface using firewall rules
- Monitor for unauthorized access attempts to the /api/backup endpoint
🔍 How to Verify
Check if Vulnerable:
curl -v http://<nginx-ui-host>:<port>/api/backup -H 'Accept: application/json' | grep -i 'x-backup-security'Check Version:
Check Nginx UI version in web interface or configuration filesVerify Fix Applied:
Attempt to access /api/backup endpoint without authentication - should return 401/403 error📡 Detection & Monitoring
Log Indicators:
- Unauthenticated requests to /api/backup endpoint
- Large backup file downloads from Nginx UI
Network Indicators:
- HTTP GET requests to /api/backup without authentication headers
- Unusual outbound traffic patterns after backup access
SIEM Query:
source="nginx-ui" AND (uri_path="/api/backup" AND NOT auth_token=*)