CVE-2019-6340

Several field types in Drupal 8.5.x and 8.6.x fail to properly sanitize data arriving from non-form sources (CWE-502, deserialization of untrusted data), which can lead to arbitrary PHP code execution on the server. The flaw is triggered remotely when a site has the Drupal 8 RESTful Web Services (rest) core module enabled and accepts PATCH or POST requests, or when other web services modules are enabled, such as JSON:API on Drupal 8 or the Services and RESTful Web Services contributed modules on Drupal 7. A successful attack yields unauthenticated remote code execution with high impact on confidentiality, integrity, and availability, typically running as the web server user. Only Drupal sites meeting the web-services conditions are affected: Drupal 8 sites running versions before 8.5.11 or 8.6.10, and Drupal 7 sites using the Services or RESTful Web Services contributed modules. The flaw has public proof-of-concept exploits on Exploit-DB, was reported as under active exploitation shortly after disclosure, and is listed in CISA's Known Exploited Vulnerabilities catalog (added 2022-03-25).

What to do: Upgrade Drupal 8 core to 8.5.11 or later, or 8.6.10 or later, per vendor instructions. If patching is not immediately possible, disable the RESTful Web Services and JSON:API modules or restrict untrusted PATCH/POST requests to their endpoints; Drupal 7 sites using Services or RESTful Web Services should apply the contributed module updates from this advisory. Review web server and module logs for suspicious POST/PATCH requests to REST or JSON:API routes as evidence of compromise.