Is low humidity bad for CMOS camera?
It's not specific to cameras that low humidity causes problems: -


  Too low humidity may make materials brittle


Also this: -


  a very low humidity level favors the build-up of static electricity, which may result in spontaneous shutdown of computers when discharges occur


This is stated on this wiki page and I read "computers" as any non-trivial electronic circuit.

The full paragraph is: -


  Many electronic devices have humidity specifications, for example, 5%
  to 45%. At the top end of the range, moisture may increase the
  conductivity of permeable insulators leading to malfunction. Too low
  humidity may make materials brittle. A particular danger to electronic
  items, regardless of the stated operating humidity range, is
  condensation. When an electronic item is moved from a cold place (e.g.
  garage, car, shed, an air conditioned space in the tropics) to a warm
  humid place (house, outside tropics), condensation may coat circuit
  boards and other insulators, leading to short circuit inside the
  equipment. Such short circuits may cause substantial permanent damage
  if the equipment is powered on before the condensation has evaporated.
  A similar condensation effect can often be observed when a person
  wearing glasses comes in from the cold (i.e. the glasses become
  foggy).[23] It is advisable to allow electronic equipment to
  acclimatise for several hours, after being brought in from the cold,
  before powering on. Some electronic devices can detect such a change
  and indicate, when plugged in and usually with a small droplet symbol,
  that they cannot be used until the risk from condensation has passed.
  In situations where time is critical, increasing air flow through the
  device's internals, such as removing the side panel from a PC case and
  directing a fan to blow into the case, will reduce significantly the
  time needed to acclimatise to the new environment.
  
  In contrast, a very low humidity level favors the build-up of static
  electricity, which may result in spontaneous shutdown of computers
  when discharges occur. Apart from spurious erratic function,
  electrostatic discharges can cause dielectric breakdown in solid state
  devices, resulting in irreversible damage. Data centers often monitor
  relative humidity levels for these reasons.