CVE-2026-9558

State: Published
Severity: 9.9 Critical
Published: May 29, 2026
Updated: May 29, 2026
Reserved: May 26, 2026

Description

A Server-Side Template Injection (SSTI) vulnerability exists in Mautic's 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 abuse this to execute arbitrary code on the hosting server (Remote Code Execution) or access restricted system files and configuration settings.

Scores

CVSS	Score	Vector	Source
3.1	9.9 Critical	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H	Mautic

Weaknesses

CWE-1336 Improper Neutralization of Special Elements Used in a Template Engine

Affected Products

Product	Versions
mautic/core	1.3.0 to before 4.4.20Affected 5.0.0 to before 5.2.11Affected 6.0.0 to before 6.0.9Affected 7.0.0 to before 7.1.2Affected

References

https://github.com/mautic/mautic/security/advisories/GHSA-9fx4-7cmj-47vg

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