Mautic up to 4.4.19/5.2.10/6.0.8/7.1.1 special elements used in a template engine

Summaryinfo

A vulnerability described as critical has been identified in Mautic up to 4.4.19/5.2.10/6.0.8/7.1.1. This issue affects some unknown processing. Executing a manipulation can lead to improper neutralization of special elements used in a template engine. This vulnerability is tracked as CVE-2026-9558. The attack can be launched remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Mautic up to 4.4.19/5.2.10/6.0.8/7.1.1. It has been declared as critical. This vulnerability affects an unknown code block. The manipulation with an unknown input leads to a improper neutralization of special elements used in a template engine vulnerability. The CWE definition for the vulnerability is CWE-1336. The product uses a template engine to insert or process externally-influenced input, but it does not neutralize or incorrectly neutralizes special elements or syntax that can be interpreted as template expressions or other code directives when processed by the engine. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The weakness was disclosed by Onurcan Genç. The advisory is available at github.com. This vulnerability was named CVE-2026-9558 since 05/26/2026. The exploitation appears to be easy. The attack can be initiated remotely. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1221 by the MITRE ATT&CK project.

Upgrading to version 4.4.20, 5.2.11, 6.0.9 or 7.1.2 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-1724). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• Open Source Mautic

Productinfo

Name

• Mautic

Version

• 4.4.0
• 4.4.1
• 4.4.2
• 4.4.3
• 4.4.4
• 4.4.5
• 4.4.6
• 4.4.7
• 4.4.8
• 4.4.9
• 4.4.10
• 4.4.11
• 4.4.12
• 4.4.13
• 4.4.14
• 4.4.15
• 4.4.16
• 4.4.17
• 4.4.18
• 4.4.19
• 5.2.0
• 5.2.1
• 5.2.2
• 5.2.3
• 5.2.4
• 5.2.5
• 5.2.6
• 5.2.7
• 5.2.8
• 5.2.9
• 5.2.10
• 6.0.0
• 6.0.1
• 6.0.2
• 6.0.3
• 6.0.4
• 6.0.5
• 6.0.6
• 6.0.7
• 6.0.8
• 7.1.0
• 7.1.1

License

• open-source

Website

• Product: https://github.com/mautic/mautic/

CPE 2.3info

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CPE 2.2info

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Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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