Andrew Bartlett discovered that Samba, a SMB/CIFS file, print, and login
server for Unix, may map domain users to local users in an undesired
way. This could allow a user in an AD domain to potentially become root
on domain members.
A new parameter "min domain uid" (default 1000) has been added to
specify the minimum uid allowed when mapping a local account to a domain account.
For the oldstable distribution (buster), this problem has been fixed
in version 2:4.9.5+dfsg-5+deb10u2. Additionally the update mitigates CVE-2020-25722. Unfortunately the changes required to fix additional
CVEs affecting Samba as an AD-compatible domain controller are too
invasive to be backported. Thus users using Samba as an AD-compatible
domain controller are encouraged to migrate to Debian bullseye. From
this point onwards AD domain controller setups are no longer supported
in Debian oldstable.
We recommend that you upgrade your samba packages.