fidzu : php

By generating and tricking a user into visiting a malicious URL, an attacker can perform site defacement.

The defacement is not stored and is only present when the URL has been crafted for that purpose. Only the defacement is present, so no other site content (such as branding) is rendered.

Drupal core contains a chain of methods that is exploitable when an insecure deserialization vulnerability exists on the site. This so-called "gadget chain" presents no direct threat, but is a vector that can be used to achieve remote code execution if the application deserializes untrusted data due to another vulnerability.

It is not directly exploitable.

This issue is mitigated by the fact that in order for it to be exploitable, a separate vulnerability must be present to allow an attacker to pass unsafe input to unserialize(). There are no such known exploits in Drupal core.

The core system module handles downloads of private and temporary files. Contrib modules can define additional kinds of files (schemes) that may also be handled by the system module.

In some cases, files may be served with the HTTP header Cache-Control: public when they should be uncacheable. This can lead to some users getting cached versions of files with information they should not be able to access. For example, files may be cached by Varnish or a CDN.

This vulnerability is mitigated by the following:

1. Drupal must be configured to handle non-public files using a custom or contributed module providing an additional file scheme.
2. An attacker must know to request a file that has previously been
   requested by a more-privileged user, and that file must still be cached.