Unbounded handle_error recursion enables denial of service in AshOban triggers

Summary

Uncontrolled Recursion vulnerability in ash-project ash_oban allows a user who can drive a trigger's on_error action to fail on the final attempt to exhaust worker CPU and memory, denying service.

The generated worker's atomic handle_error/4 runs the trigger's on_error action on a job's final attempt inside a rescue that, when the action itself raises, calls handle_error/4 again with the same job. The job's attempt still equals max_attempts, so it re-enters the same clause and re-runs the failing action, with no exit. Any deterministic on_error failure (a data-layer outage, a misconfigured action, or a record the action rejects) loops forever; because the recursive call is not in tail position, each iteration retains a formatted stacktrace and the process heap grows without bound while the failing statement is re-issued against the data layer until the runtime kills the worker.

This issue affects ash_oban: from 0.8.0-rc.1 before 0.8.14.

Configurations

A trigger must declare an on_error action and run through the atomic worker branch. An attacker needs only to drive that on_error action into a deterministic failure (for example by pushing the record into a state the action rejects) and let the job reach its final attempt.