The app/process-api-response-headers action accepts fake Craft API response headers from any authenticated control panel user. A non-admin user with only accessCp can place newline characters in X-Craft-Plugin-Licenses. Craft passes this value to its .env writer without removing the newlines.
This lets the user insert a new attacker-known CRAFT_SECURITY_KEY into .env. After Craft loads that key, the user can forge a signed login redirect containing a Twig system() callback. This is different from the previous report.
That report reads the existing key through a Twig sandbox bypass. This report replaces the key through fake API headers and CRLF injection. Fixing either source does not fix the other.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service
CVSS Vector v4.0
Weakness Type (CWE)
References 4
https://github.com/craftcms/cms
7004884b-51e2-48e8-b4a2-5ca29e80453e
https://github.com/craftcms/cms/releases/tag/5.11.2
7004884b-51e2-48e8-b4a2-5ca29e80453e
https://github.com/craftcms/cms/security/advisories/GHSA-9hp6-3565-gvh5
7004884b-51e2-48e8-b4a2-5ca29e80453e
https://www.hckrt.com/hacktivity/HCKRT-WM3VSE
7004884b-51e2-48e8-b4a2-5ca29e80453e