Copssh version 7.1.0 installers come with OpenSSH 8.1 with some security related updates:

• ssh(1), sshd(8), ssh-add(1), ssh-keygen(1): an exploitable integer overflow bug was found in the private key parsing code for the XMSS key type. This key type is still experimental and support for it is not compiled by default. No user-facing autoconf option exists in portable OpenSSH to enable it. This bug was found by Adam Zabrocki and reported via SecuriTeam's SSD program.
• ssh(1), sshd(8), ssh-agent(1): add protection for private keys at rest in RAM against speculation and memory side-channel attacks like Spectre, Meltdown and Rambleed. This release encrypts private keys when they are not in use with a symmetric key that is derived from a relatively large "prekey" consisting of random data (currently 16KB).

LibreSSL is also updated to 3.0.1, including  a port of Billy Brumley's fix for CVE-2019-1547 in OpenSSL 1.1.1.

-- Incompatibility note for Copssh versions 6.x and earlier --

As of version 7.0, Copssh uses Cygwin 3.x libraries, introducing major and backwards-incompatible changes, thus requiring a reinstallation. You can follow our instructions here, to refresh your installation withour losing your existing setup.

Thanks to major changes in Cygwin, Copssh doesn't need a dedicated service account any longer and is run by the local system account.

The logic behind the sftp home directory isolation is now improved by introducing symbolic link folders: Each activated user gets a symbolic link folder /home/___username , pointing to the home directory provided via the User Activation wizard, resulting with a more stable and less error-prone solution.  A small patch avoiding messages "bad ownership or modes for chroot directory" (non-relevant for a Copssh installation), is also introduced. NB! As always mentioned, even if the home directory isolation works as expected, you should use NTFS permissions on your file systems to achieve better security.