A server-side template injection vulnerability exists in the Twig theme rendering sandbox of Mautic. The sandbox introduced to restrict user-uploaded theme templates (the fix for GHSA-9fx4-7cmj-47vg) does not fully enforce its restrictions,…

A server-side template injection vulnerability exists in the Twig theme rendering sandbox of Mautic. The sandbox introduced to restrict user-uploaded theme templates (the fix for GHSA-9fx4-7cmj-47vg) does not fully enforce its restrictions, allowing a crafted theme template to escape the sandbox. An authenticated user with the core:themes:create permission can upload a malicious theme whose template is later rendered, resulting in execution of arbitrary code on the server with the privileges of the web server process. This allows the attacker to execute operating system commands, read server-side files including configuration files and database credentials, write files, and reach internal services. In default installations the core:themes:create permission is granted to the Administrator role, and in multi-operator setups it may be delegated to other roles. This is an incomplete fix for GHSA-9fx4-7cmj-47vg.

Source published

26 Oct 2026 12:39:14 UTC

Source modified

26 Oct 2026 15:35:53 UTC

Observed here

26 Oct 2026 16:35:30 UTC

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CVSS 3.1 · 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H