MISP contains a vulnerability in its background job dispatch mechanism that allows remote code execution as the web user. Background job arguments are passed directly as the argv of the CakePHP console process. CakePHP's ShellDispatcher::_parsePaths() scans the entire argv for path switches (-app, --app, -working, --working, -root, --root, -webroot, --webroot) and uses the following element as the application root. The events/contact endpoint passes user-controlled fields (message and person) into job arguments without validation. An attacker who can submit the contact form can set the person field to a reserved switch and the message field to a phar:// URI pointing to a malicious archive. The CakePHP bootstrap then includes Config/core.php from within that archive, executing attacker-controlled PHP code with the privileges of the web user.
The vulnerability requires the ability to submit the events/contact form (or any other endpoint that forwards user input into background job arguments). No special timing or race condition is required; the attack is deterministic once the crafted parameters are accepted. The impact is full remote code execution in the context of the MISP web server process, allowing data exfiltration, persistence, and lateral movement within the host.