CVE-2026-9558

CRITICAL

Mautic - Authenticated Server-Side Template Injection via Theme Engine

Title source: llm

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.

References (1)

Core 1

Core References

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

Scores

CVSS v3 9.9

EPSS 0.0020

EPSS Percentile 41.3%

Attack Vector NETWORK

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

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact total

Details

CWE

CWE-1336

Status published

Published May 29, 2026

Tracked Since May 29, 2026