Improper Neutralization of Special Elements Used in a Template Engine Affecting mautic/core-lib package, versions <5.2.11>=6.0.0-alpha, <6.0.9>=7.0.0-alpha, <7.1.2
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PHP-MAUTICCORELIB-17132597
- published2 Jun 2026
- disclosed29 May 2026
- creditOnurcan Genç, Daniel Zhang, Tuan Do
Introduced: 29 May 2026
CVE-2026-9558 (opens in a new tab)How to fix?
Upgrade mautic/core-lib to version 5.2.11, 6.0.9, 7.1.2 or higher.
Overview
Affected versions of this package are vulnerable to Improper Neutralization of Special Elements Used in a Template Engine in the theme engine due to rendering uploaded Twig templates without a sandbox or strict function restrictions. An attacker can execute arbitrary code on the hosting server or access restricted system files and configuration settings by uploading or creating malicious themes with crafted templates.
Note: This is only exploitable if the attacker has permissions to create or upload themes.
Workaround
This vulnerability can be mitigated by restricting theme upload and creation permissions (core:themes:create) to only highly trusted administrators.