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().
{
"cna_assigner": "VulnCheck",
"cwe_ids": [
"CWE-94"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86730.json"
}{
"extracted_events": [
{
"range": [
{
"introduced": "5.0.0-RC1"
},
{
"fixed": "5.10.12"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StandardRange"
},
{
"range": [
{
"introduced": "0"
},
{
"fixed": "5.10.12"
}
],
"source": "DESCRIPTION"
}
]
}