CVE-2026-33157: Craft CMS: Potential authenticated Remote Code Execution via malicious attached Behavior

Severity: high (CVSS 7.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-03-24 · updated 2026-06-17
Weakness: CWE-470

Description

Craft CMS is a content management system (CMS). From version 5.6.0 to before version 5.9.13, a Remote Code Execution (RCE) vulnerability exists in Craft CMS, it can be exploited by any authenticated user with control panel access. This is a bypass of a previous fix. The existing patches add cleanseConfig() to assembleLayoutFromPost() and various FieldsController actions to strip Yii2 behavior/event injection keys ("as" and "on" prefixed keys). However, the fieldLayouts parameter in ElementIndexesController::actionFilterHud() is passed directly to FieldLayout::createFromConfig() without any sanitization, enabling the same behavior injection attack chain. This issue has been patched in version 5.9.13.

Affected products

craftcms cms: from 5.6.0 before 5.9.13 — fixed in 5.9.13

How to fix

Upgrade to a fixed version: craftcms cms 5.9.13. Check the vendor advisory for mitigations.

References

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