Invalid access to memory on connecting through a tunnel

Connecting to a host through a tunnel. Tunnel auth uses primary key with password.

WinSCP 5.2.5

Error message:
Invalid access to memory.
Authentication log (see session log for details):
Using username "sasapp".
Authenticating with public key "sergey".

Authentication failed.

Thanks for your report.

This bug is being tracked already:
https://winscp.net/tracker/1076