Code Injection in Craft CMS - #VU159602
Published: November 6, 2026
Vulnerability identifier: #VU159602
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-94
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a low-privileged control panel user to execute arbitrary operating system commands as the PHP worker.
The vulnerability exists due to Craft CMS accepting newline characters in emulated X-Craft-Plugin-Licenses API response headers and writing them into .env through app/process-api-response-headers. A low-privileged control panel user with accessCp can inject an attacker-known CRAFT_SECURITY_KEY and, after Craft loads it, forge a signed login redirect that executes commands.
Affected software
Craft CMS
Remediation
Install security update from vendor's website.
Craft CMS - addressed in versions 4.18.9, 5.11.2