MISP Sharing Group Quick-Edit Actions Allow CSRF via State-Changing GET Requests

MISP contains a cross-site request forgery (CSRF) vulnerability in the sharing group quick-edit functionality. The addOrg, removeOrg, addServer, and removeServer actions share the __initialiseSGQuickEdit() helper, where the HTTP method validation intended to restrict these operations to POST requests was commented out.

As a result, these state-changing actions could be invoked using GET requests. An attacker could craft a URL targeting one of the affected actions and cause an authenticated MISP user with sufficient privileges to request it, for example through a malicious link or embedded web resource.

Successful exploitation could modify the membership of a MISP sharing group without the victim intentionally performing the operation. Depending on the action performed, an attacker could add or remove organisations or servers from a sharing group, potentially granting unintended access to information distributed through that sharing group or disrupting legitimate information sharing.

The patch restores HTTP method enforcement centrally in __initialiseSGQuickEdit() by calling allowMethod(['post']), ensuring that all four affected quick-edit operations require POST requests and are therefore subject to the application's normal protections for state-changing requests.