Samba 4.12.6 is also affected by the recent "zerologon" vulnerability discovered in MS Windows:

https://www.samba.org/samba/security/CVE-2020-1472.html

CVSSv3 rating:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (9.8)

Samba 4.12.7 has been released to fix the issue on 2020-09-18, and the freshly released Samba 4.13.0 from yesterday should fix the issue as well.