Some field types do not properly sanitize data from non-form sources in Drupal 8.5.x before 8.5.11 and Drupal 8.6.x before 8.6.10. This can lead to arbitrary PHP code execution in some cases. A site is only affected by this if one of the following conditions is met: The site has the Drupal 8 core RESTful Web Services (rest) module enabled and allows PATCH or POST requests, or the site has another web services module enabled, like JSON:API in Drupal 8, or Services or RESTful Web Services in Drupal 7. (Note: The Drupal 7 Services module itself does not require an update at this time, but you should apply other contributed updates associated with this advisory if Services is in use.)

References

• https://nvd.nist.gov/vuln/detail/CVE-2019-6340
• https://www.drupal.org/sa-core-2019-003
• https://www.synology.com/security/advisory/Synology_SA_19_09
• http://www.securityfocus.com/bid/107106
• https://github.com/FriendsOfPHP/security-advisories/blob/master/drupal/core/CVE-2019-6340.yaml
• https://github.com/FriendsOfPHP/security-advisories/blob/master/drupal/drupal/CVE-2019-6340.yaml
• https://www.exploit-db.com/exploits/46452
• https://www.exploit-db.com/exploits/46459
• https://www.exploit-db.com/exploits/46510