Is CVE-2026-9558 actively exploited?

No active exploitation of CVE-2026-9558 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-9558 be exploited remotely?

Yes. CVE-2026-9558 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-9558?

CVE-2026-9558 has a CVSS score of 9.9 (CRITICAL).

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CRITICAL

CVE-2026-9558

CWE-1336Published: May 29, 2026· Updated: May 29, 2026

9.9

CVSS v3.1

EPSS:0.20%probability of exploitation in 30 daysPercentile:41.3th

Official 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.

NVD Source

Risk Analysis

This critical vulnerability in Mautic's theme engine allows authenticated users with theme upload permissions to execute arbitrary code or access sensitive system files. The CVSS score of 9.9 highlights the severe impact, as it can lead to full system compromise. There is no EPSS score to indicate exploitation likelihood, and it is not currently in CISA's KEV catalog.

No public exploit is known for this vulnerability. While it requires authentication, the network attack vector and low attack complexity make it a significant threat for an attacker with appropriate privileges.

Recommended Action

Organizations using Mautic should ensure that only trusted users have permissions to create or upload themes. Apply any available patches or upgrades to the Mautic theme engine to address this Server-Side Template Injection vulnerability.

Generated by the CTIWATCH analysis pipeline from this CVE's metadata (CVSS, EPSS, KEV status, exploit intelligence). Verify against vendor advisories before acting.

Technical Analysis

CVE-2026-9558 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.9.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.