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CVE-2026-9558

Published: May 29, 2026Updated: May 29, 2026 Sources: CVE List NVD

9.9CVSS

CRITICAL

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.

EPSS Score

0.2%

Top 58.7%

CISA KEV

Not in KEV

Exploits

No Known Exploits

Remediation

Workaround Only

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:LPrivileges Required

Low

UI:NUser Interaction

None

Scope

S:CScope

Changed

Impact

C:HConfidentiality

High

I:HIntegrity

High

A:HAvailability

High

Weaknesses

CWE-1336

Affected Products

Exploitability

Workaround Available

References

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

github.com

Timeline

Published

May 29, 2026

Last Updated

May 29, 2026

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