Vulnerability · Published Sep 8, 2026 · Assigned by VulnCheck

CVE-2026-86730Craft CMS 5.0.0-RC1 before 5.10.12 Behavior Injection RCE

High 8.8

In plain English

A high-severity code injection in cms from craftcms. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 54% of all known vulnerabilities).

Severity (CVSS 3.1)8.8High

Exploit odds (30 days)0.7%top 46.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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().

Affected products (as reported)

Vendor	Product	Versions
craftcms	cms	5.0.0-RC1 – before 5.10.12

Weakness: CWE-94 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

GitHub Security Advisory (GHSA-qj4v-m29p-fj4m) vendor-advisory
VulnCheck Advisory: Craft CMS 5.0.0-RC1 before 5.10.12 Behavior Injection RCE third-party-advisory