Attack Chain

1. Initial Access: An attacker obtains valid credentials for a Mautic user account with API access permissions.
2. API Request Crafting: The attacker crafts a specially malformed API request targeting Mautic's contact filtering endpoint (e.g., /api/contacts).
3. SQL Payload Injection: The malicious request includes an SQL injection payload embedded within nested query parameters, designed to bypass Mautic's existing input sanitization for CVE-2026-4776.
4. Backend Processing: Mautic's API processes the request, and due to the vulnerability, fails to properly sanitize the injected SQL commands.
5. SQL Execution: The unsanitized SQL payload is executed directly against the backend database server (e.g., MySQL, PostgreSQL).
6. Data Exfiltration: The malicious SQL query extracts sensitive information from the database, such as administrator credentials, system configurations, or PII.
7. Data Retrieval: The extracted sensitive data is returned as part of the legitimate API response, allowing the authenticated attacker to retrieve it.

Impact

Successful exploitation of CVE-2026-4776 grants an authenticated user with API access the ability to execute arbitrary SQL queries against Mautic's backend database. This has severe implications, as it enables unauthorized access and retrieval of sensitive database contents. This includes, but is not limited to, user credentials (potentially including hashed passwords), critical system configurations, and all personal identifiable information (PII) stored for marketing contacts. This bypasses standard data access permissions, potentially exposing millions of records in larger Mautic deployments and leading to significant data breaches, reputational damage, and regulatory penalties.

Recommendation

• Patch CVE-2026-4776 immediately: Upgrade Mautic to one of the patched versions: 7.1.2, 6.0.9, 5.2.11, or 4.4.20.
• Implement WAF rules: Deploy a Web Application Firewall (WAF) and configure rules to detect and block common SQL injection patterns, especially those targeting query parameters of Mautic API endpoints as outlined in the Sigma rule.
• Restrict API access: If immediate patching is not possible, temporarily disable Mautic API access or restrict API permissions to only highly trusted accounts as a mitigation described in the brief.
• Monitor webserver logs: Deploy the provided Sigma rule to your SIEM to detect attempts to exploit CVE-2026-4776 by monitoring your webserver logs for suspicious API requests.