Updates released for versions 8.2 and 8.3 of the Drupal content management system (CMS) address a critical access bypass vulnerability.
The flaw, discovered by Drupal developer Samuel Mortenson and tracked as CVE-2017-6919, has been classified as critical by the Drupal security team, but it only affects websites if certain conditions are met.
Websites are vulnerable to attacks exploiting this flaw if they have the RESTful Web Services (RESTWS) module enabled and they allow PATCH requests. The attacker must also be able to register an account on the targeted site.
Nevertheless, the security hole is potentially serious, which is why Drupal developers have released a patch not only for the 8.3 branch, but also for the 8.2 series, which has reached end of life and will not receive other updates.
Drupal has advised 8.2.x users to update to Drupal 8.2.8, but still recommends updating to Drupal 8.3 at a later time. In the case of Drupal 8.3, the vulnerability has been patched with the release of version 8.3.1. Drupal 7 is not affected.
Vulnerabilities involving the RESTWS module have been known to be exploited in the wild. In September 2016, researchers spotted attempts to exploit a RESTWS flaw that had been patched two months earlier.
The latest updates come only one day after Drupal announced the availability of a patch for a critical flaw affecting a popular third-party module.
The References module, used by more than 121,000 websites, had not been updated since 2013 and Drupal flagged it as unsupported. However, Drupal has managed to find a new maintainer for the module and the security hole has been fixed.