Wiring troubles ????

If the fault is in a bulb socket it would have to be at the rear.
When a chassis ground fails at a front fixture the park lamp circuit grounds through the turn circuit so a turn indicator on the dash will come on with the park lamps.
By the same token when a brake fixture looses its chassis ground it might ground through the park circuit which lights up all the park lamps. That should blow a the brake light fuse or at least cook the bulb where the fault is.
Too much junk in the trunk can chew the rear light harness. Faulty trailer light harness wiring is another common cause.