Some say this, but the consensus is that meteorites play as the perfect time capsule. Some organisms on earth can take absolutely loads of radiation and are not effective. Tardigrades have been experimented on, they can pretty much survive outerspace.
You won't get any arguments from me regarding the hardiness of some microbial life.
So far on Earth life has been found thriving in Ocean depths around "Black smokers" and Hydrothermal vents near temperatures in excess of boiling water, and also around spent nuclear fuel rods.
Could similar life be transported through outer space?? I don't see why not.