Security advisories for Drupal core

Drupal Core has a rarely used feature, provided by an underlying library, which allows certain attributes of incoming HTTP requests to be overridden.

This functionality can be abused in a way that may cause Drupal to cache response data that it should not. This can lead to legitimate requests receiving inappropriate cached responses (cache poisoning).

This could be exploited in various ways:

Drupal core contains a potential PHP Object Injection vulnerability that (if combined with another exploit) could lead to Arbitrary File Inclusion. Techniques exist to escalate this attack to Remote Code Execution. 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.

Drupal core doesn't sufficiently filter error messages under certain circumstances, leading to a reflected Cross Site Scripting vulnerability (XSS).

Sites are encouraged to update. There are not yet public documented steps to exploit this, but there may be soon given the nature of this issue.

This issue is being protected by Drupal Steward. Sites that use Drupal Steward are already protected, but are still encouraged to upgrade in the near future.

Drupal core contains a potential PHP Object Injection vulnerability that (if combined with another exploit) could lead to Remote Code Execution. 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.