High severity · published Sep 8, 2026
CVE-2026-86730
Craft CMS 5.0.0-RC1 before 5.10.12 Behavior Injection RCE
8.8
CVSS
0.7%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 53% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CM
cms · craftcms
5.0.0-RC1 before 5.10.12 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-86730
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-86730
github.com
https://github.com/craftcms/cms/security/advisories/GHSA-qj4v-m29p-fj4m
www.vulncheck.com
https://www.vulncheck.com/advisories/craft-cms-5.0.0-rc1-before-5.10.12-behavior-injection-rce
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