CVE-2026-9558

Name of the Vulnerable Software and Affected Versions Mautic versions prior to 7.1.2 Mautic versions prior to 6.0.9 Mautic versions prior to 5.2.11 Mautic versions prior to 4.4.20

Description A Server-Side Template Injection (SSTI) issue exists in the theme engine. The platform renders uploaded Twig templates without a sandbox or strict function restrictions. Authenticated users with permissions to create or upload themes can exploit this to execute arbitrary code on the hosting server (Remote Code Execution) or access restricted system files and configuration settings.

Recommendations Update to version 7.1.2. Update to version 6.0.9. Update to version 5.2.11. Update to version 4.4.20. Restrict theme upload and creation permissions core:themes:create to only highly trusted administrators.