In Drupal Core versions 7.x prior to 7.62, 8.6.x prior to 8.6.6 and 8.5.x prior to 8.5.9; Drupal core uses the third-party PEAR Archive_Tar library. This library has released a security update which impacts some Drupal configurations. Refer to CVE-2018-1000888 for details
https://www.drupal.org/sa-core-2019-001
https://www.debian.org/security/2019/dsa-4370
https://lists.debian.org/debian-lts-announce/2019/02/msg00032.html