---
id: CVE-2026-86730
title: >-
  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
summary: >-
  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 element…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-94
vendor: craftcms
product: cms
affected:
  - cms >= 5.0.0-RC1 < 5.10.12
published: '2026-09-08'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T19:53:13.400'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-86730'
references:
  - url: 'https://github.com/craftcms/cms/security/advisories/GHSA-qj4v-m29p-fj4m'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/craft-cms-5.0.0-rc1-before-5.10.12-behavior-injection-rce
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-08T15:36:07.413468Z'
ingestedAt: '2026-09-08T15:33:26.987Z'
epss: 0.00707
epssPercentile: 0.51427
---

## Overview

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().

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.