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.

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Advisories

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Fixes

Solution

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Workaround

There are no official workarounds. To mitigate this vulnerability without upgrading, restrict the core:themes:create permission to trusted administrator accounts only and do not delegate theme creation to operator-level roles.

History

Mon, 26 Oct 2026 14:00:00 +0000

Type Values Removed Values Added
Description 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.
Weaknesses CWE-1336
References
Metrics cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Mautic

Published:

Updated: 2026-10-26T12:39:14.432Z

Reserved: 2026-10-22T06:39:15.178Z

Link: CVE-2026-115189

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-10-26T14:16:30.203

Modified: 2026-10-26T14:21:33.887

Link: CVE-2026-115189

cve-icon Redhat

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cve-icon OpenCVE Enrichment

No data.

Weaknesses