LongPIBench: A Long-Context Benchmark for Prompt Injection
InconclusivePlannedFindingclaim-heuristic-attacks-effective

On long-context document tasks, heuristic prompt-injection attacks substantially increase attack success rate over no-attack baselines, and Authority spoof is generally the strongest listed heuristic.

Source: paper:pp. 7-8, Section 4.5, Table 1