Cross-site scripting in Craft CMS - #VU159609
Published: November 6, 2026
Vulnerability identifier: #VU159609
CSH Severity: Low
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N]
CVE-ID: N/A
CWE-ID: CWE-79
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a low-privilege control panel user to execute JavaScript in an administrator’s browser session.
The vulnerability exists due to unescaped rendering of a cached licensed-domain string in the Craft CMS control panel’s license-mismatch warning. A low-privilege control panel user can submit a malicious license string through app/process-api-response-headers to poison the cache, causing stored JavaScript to execute when an administrator opens the control panel.
Affected software
Craft CMS
Remediation
Install security update from vendor's website.
Craft CMS - update to 5.11.4