8.8 High

A server-side template injection vulnerability exists in the Twig theme rendering sandbox of Mautic.

CVE-2026-115189

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.

Assessment

CVSS: 8.8 (v3.1)
Severity: High
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 26 October 2026
Last updated: 26 October 2026
Weakness: CWE-1336
Assigner: security@mautic.org

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

At the source

References

https://github.com/mautic/mautic/security/advisories/GHSA-h7pm-79gc-8867

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