Algorithmic-complexity denial of service in AshPaperTrail full-diff list tracking

Inefficient Algorithmic Complexity vulnerability in ash-project ash_paper_trail allows a user who can submit a large array attribute to a paper-trailed create or update action to cause a denial of service through excessive CPU and memory use.

With full-diff change tracking, AshPaperTrail.ChangeBuilders.FullDiff.ListChange pairs each prior array element against the new list by rebuilding the remaining-elements accumulator with acc ++ [tuple] on every step, copying the growing list each time, so the pairing scales cubically in the array length. Nothing bounds the length and the value comes straight from action input, so one request carrying a large accepted {:array, _} attribute forces tens of seconds of CPU and multi-gigabyte allocations.

This issue affects ash_paper_trail: from 0.1.1 before 0.7.0.

The resource must use full-diff change tracking (change_tracking_mode :full_diff) and accept an array attribute with no effective maximum length, reached through a create or update action exposed to the input.