Password authentication in FIPS-compliant mode

The documentation states, that:

"The VNC protocol has limited support for password based authentication. (...) Password authentication is not supported when operating in FIPS 140-2 compliance mode as it requires the use of the DES cipher."

Would it be possible for qemu to use a different cipher and re-enable password as an option in VNC console? Is there a technical reason for not using a stronger cipher?