I was heading to Dragon's Bridge in order to tail Gaius Maro on his way to Solitude for the quest Breaching Security. However, as soon as I arrive in town, Gaius and his father instantly attack me. I did some research on UESP and found that their inexplicable aggression is a bug.

Are there any workarounds for this issue?

Try opening the console, click on them and use the commands

disableenable

one after another.

If it doesn't work, use the commands

killressurect

one after another.

You do not mention on what platform you are playing, so this fix is obviously for pc players.