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Vulnerability record · CVE-2026-9558 · published 29 May 2026

CVE-2026-9558: A Server-Side Template Injection (SSTI) vulnerability exists in Mautic's theme engine.

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.

9.9 CVSS 3.1 Critical EPSS 0.79% · top 45.6% CWE-1336 · CWE-1336 Deferred
9.9CVSS 3.1 base score
0.79%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
1References
21 Jul 2026Last modified by NVD

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.

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

References

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

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-9558), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.