Bugs 522476 & 652334 have already been filed about VNC password length. This bug is about SPICE password length instead.

Unlike VNC, SPICE passwords are not limited to 8 characters. The upstream SPICE code has:
#define SPICE_MAX_PASSWORD_LENGTH 60

This is impacting me because in order to connect to my VMs running on Fedora 21 with KVM via SPICE, I have to reduce their password length to 8 characters or use an alternate SPICE client (like remote-viewer, which is part of the virt-viewer package.)

Test Systems:
Client: Fedora 22 x86_64 alpha with vinagre 3.16.0-1.fc22.
KVM/SPICE host: Fedora 21 x86_64

Steps to reproduce:
1. In virt-manager on the KVM host, define the "Display" as being of "Type" "Spice server", with a password longer than 8 characters. I have both "Port" and "TLS Port" set to "Auto". The auto-assigned "Port" is 5901, and that port is what I specify in the clients. Also, set the "Address" to "All interfaces" so that the VM is accessible from remote SPICE clients.
2. Test connecting to the SPICE host with remote-viewer. Enter the URL like "spice://mothership:5901". You should then be prompted for the password. It will accept the long password and connect.
3. Try to "Connect" to the SPICE host (e.g, "mothership:5901") with Vinagre. As you try to type the 9th character, it is ignored. If you type the full length password anyway and hit connect, you will be re-prompted for the password.