CVE-2025-56425
📋 TL;DR
This vulnerability allows authenticated remote attackers to inject arbitrary SMTP commands via crafted input to the /osrest/api/organization/sendmail endpoint in enaio's AppConnector component. Attackers can potentially send unauthorized emails, exfiltrate data, or use the SMTP server for further attacks. Affected systems include enaio versions 10.10, 11.0, and 11.10 with AppConnector component versions up to 10.10.0.183, 11.0.0.183, and 11.10.0.183 respectively.
💻 Affected Systems
- enaio AppConnector component
📦 What is this software?
Enaio by Optimal Systems
Enaio by Optimal Systems
Enaio by Optimal Systems
⚠️ Risk & Real-World Impact
Worst Case
Full SMTP server compromise allowing email spoofing, data exfiltration via email, SMTP relay attacks, and potential credential harvesting through phishing campaigns.
Likely Case
Unauthorized email sending, SMTP command injection leading to information disclosure, and potential use of the SMTP server for spam or phishing.
If Mitigated
Limited impact with proper input validation and SMTP server restrictions, potentially only allowing email sending from authorized addresses.
🎯 Exploit Status
Exploitation requires authenticated access but the injection mechanism appears straightforward based on the CWE-77 (Command Injection) classification.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 10.10.0.183, 11.0.0.183, and 11.10.0.183 respectively
Vendor Advisory: https://www.optimal-systems.de/enaio
Restart Required: Yes
Instructions:
1. Check current AppConnector version. 2. Update to patched versions: >10.10.0.183 for enaio 10.10, >11.0.0.183 for enaio 11.0, >11.10.0.183 for enaio 11.10. 3. Restart the AppConnector service. 4. Verify the fix by testing the sendmail endpoint with malicious input.
🔧 Temporary Workarounds
Block vulnerable endpoint
allRestrict access to the /osrest/api/organization/sendmail endpoint using web application firewall or network controls
# Example WAF rule to block /osrest/api/organization/sendmail
# Example nginx: location ~ ^/osrest/api/organization/sendmail { deny all; }
Implement input validation proxy
allDeploy a reverse proxy that validates and sanitizes input to the sendmail endpoint
# Configure proxy to validate email parameters
# Example: Validate email addresses and sanitize SMTP commands
🧯 If You Can't Patch
- Implement strict input validation and sanitization for all parameters sent to the sendmail endpoint
- Restrict SMTP server permissions and implement rate limiting on email sending functionality
🔍 How to Verify
Check if Vulnerable:
Check AppConnector component version against affected versions. Test the /osrest/api/organization/sendmail endpoint with SMTP command injection payloads.Check Version:
Check enaio administration interface or configuration files for AppConnector version informationVerify Fix Applied:
After patching, attempt SMTP command injection via the sendmail endpoint and verify it fails. Check that version is above the vulnerable thresholds.📡 Detection & Monitoring
Log Indicators:
- Unusual SMTP commands in application logs
- Multiple failed sendmail attempts
- SMTP commands containing injection patterns (e.g., CRLF, MAIL FROM, RCPT TO with unusual parameters)
Network Indicators:
- Unusual SMTP traffic from the AppConnector server
- SMTP commands to unexpected destinations
- High volume of email sending from single authenticated session
SIEM Query:
source="enaio_appconnector" AND (url="/osrest/api/organization/sendmail" AND (message="*CRLF*" OR message="*MAIL FROM*" OR message="*RCPT TO*"))