Hardening Agent Benchmarks with Adversarial Hacker-Fixer Loops
Agent benchmarks score submissions with outcome verifiers that are typically hand-written and brittle, leaving them open to reward hacking. We audit 1,968 tasks across five terminal-agent benchmarks and find 323 (16%) hackable by frontier models given only the task description. This corrupts both leaderboard rankings and RL training signal, yet the standard response is manual and reactive. We introduce the hacker-fixer loop, a method for building exploit-resistant verifiers without per-task manual patching. The loop alternates three LLM agents: a hacker tries to pass the verifier without solving the task, a fixer patches the verifier to reject each discovered exploit, and a solver confirm...
| Authors | Ziqian Zhong, Ivgeni Segal, Ivan Bercovich et al. |
|---|---|
| Primary category | cs.CR |
| Published | 8 June 2026 |
| Last updated at source | 8 June 2026 |
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