The Grav Email plugin (getgrav/grav-plugin-email) before 4.2.2 renders page-editor-controlled Email action parameters as unsandboxed Twig templates. An authenticated remote user with only api.access and api.pages.write permissions can place a Twig expression in header.form.process.email.body, publish the page, and submit the form to execute an arbitrary operating-system command as the account running PHP.
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