The remote Debian host is missing a security-related update.
Jann Horn discovered that the ptrace subsystem in the Linux kernel mishandles the management of the credentials of a process that wants to create a ptrace relationship, allowing a local user to obtain root privileges under certain scenarios.
Upgrade the linux packages. For the oldstable distribution (stretch), this problem has been fixed in version 4.9.168-1+deb9u4. For the stable distribution (buster), this problem has been fixed in version 4.19.37-5+deb10u1. This update includes as well a patch for a regression introduced by the original fix for CVE-2019-11478 (#930904).