script_basereplace - xforcered/python_intruder_payloads GitHub Wiki

In the fuzzing - quick and fuzzing - full lists provided with Burp Intruder by default, the token "{base}" appears, and you're meant to add a match-and-replace processing rule, but this is not ideal when you are testing multiple insertion points with different base values. This script will replace {base} with the original value at the insertion point being tested.

payload = current_payload.replace("{base}", base_value)