Ruble came under increased pressure again over last week. USD-RUB, being at 68, previous highs of 2015 as in January, February and August are not far away, which is more than inconvenient for the central bank. 

"CBR would like to cut rates again to support the tumbling economy but has to consider the ruble weakness as otherwise inflation might get out of control. So far it has banked on inflation easing notably over the coming months", says Commerzbank. 

Given today's CPI data for November is higher, that would not constitute a reason for stronger ruble arguing that this would make it less likely for the rate cuts.

There would be a greater risk then that CBR might lose control about inflation and hence would not be succeeding to create attractive real interest rates in near future, which might cause further weakness in the currency.