CVE-2026-86730: Improper Control of Generation of Code ('Code Injection') in craftcms cms
Craft CMS versions before 5.10.12 fail to properly cleanse string-typed field-layout elements, allowing authenticated control-panel users to inject Yii2 behavior attachments and event handlers. Attackers can post field-layout tab elements as JSON strings to bypass cleanse validation, then trigger arbitrary object instantiation and code execution through Craft::createObject().
AI Analysis
Technical Summary
CVE-2026-86730 is a code injection vulnerability in Craft CMS affecting versions from 5.0.0-RC1 up to but not including 5.10.12. The flaw arises from improper cleansing of string-typed field-layout elements, which allows authenticated users to inject Yii2 behavior attachments and event handlers. Attackers can submit field-layout tab elements as JSON strings to bypass cleansing validation, leading to arbitrary object instantiation and code execution via Craft::createObject(). The vulnerability has a CVSS 4.0 score of 8.7, indicating high severity, and requires low attack complexity with no user interaction.
Potential Impact
An authenticated user with control-panel access can exploit this vulnerability to execute arbitrary code on the server by injecting malicious Yii2 behavior attachments and event handlers. This could lead to full compromise of the affected Craft CMS instance, including unauthorized actions and potential data breaches.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict control-panel access to trusted users only and monitor for suspicious activity related to field-layout modifications.
CVE-2026-86730: Improper Control of Generation of Code ('Code Injection') in craftcms cms
Description
Craft CMS versions before 5.10.12 fail to properly cleanse string-typed field-layout elements, allowing authenticated control-panel users to inject Yii2 behavior attachments and event handlers. Attackers can post field-layout tab elements as JSON strings to bypass cleanse validation, then trigger arbitrary object instantiation and code execution through Craft::createObject().
CVSS v4.0
Score 8.7high
Affected software
pkg:github/craftcms/cmsRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-86730 is a code injection vulnerability in Craft CMS affecting versions from 5.0.0-RC1 up to but not including 5.10.12. The flaw arises from improper cleansing of string-typed field-layout elements, which allows authenticated users to inject Yii2 behavior attachments and event handlers. Attackers can submit field-layout tab elements as JSON strings to bypass cleansing validation, leading to arbitrary object instantiation and code execution via Craft::createObject(). The vulnerability has a CVSS 4.0 score of 8.7, indicating high severity, and requires low attack complexity with no user interaction.
Potential Impact
An authenticated user with control-panel access can exploit this vulnerability to execute arbitrary code on the server by injecting malicious Yii2 behavior attachments and event handlers. This could lead to full compromise of the affected Craft CMS instance, including unauthorized actions and potential data breaches.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict control-panel access to trusted users only and monitor for suspicious activity related to field-layout modifications.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-09-08T11:31:09.013Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6aa029bfacd9273b49d8b692
Added to database: 09/08/2026, 15:29:03 UTC
Last enriched: 09/08/2026, 15:37:35 UTC
Last updated: 09/08/2026, 22:32:31 UTC
Views: 8
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