  Detached circumplanetary disks are unstable to tilting as a result of the
stellar tidal potential. We examine how a tilted circumplanetary disk affects
the evolution of the spin axis of an oblate planet. The disk is evolved using
time-dependent equations for linear wave-like warp evolution, including terms
representing the effect of the tidal potential and planetary oblateness. For a
disk with a sufficiently large mass, we find that the planet spin quickly
aligns to the misaligned disk. The tilt of the planetary spin axis then
increases on the same timescale as the disk. This can be an efficient mechanism
for generating primordial obliquity in giant planets. We suggest that directly
imaged exoplanets at large orbital radii, where the disk mass criterion is more
likely to be satisfied, could have significant obliquities due to the tilt
instability of their circumplanetary disks.
