
ExploitGym has no answer key, which is a problem for every account of the Hugging Face break-in
System notes
ExploitGym is a 898-instance benchmark measuring whether an agent can turn an already-reported vulnerability into a working exploit, drawn from 520 userspace instances across 161 OSS-Fuzz projects, 185 V8 instances and 193 Linux kernel instances, and its code is published on GitHub.
A task counts as solved only when the agent achieves unauthorized code execution against a live containerised target, exfiltrates a secret flag, and exercises the specific named vulnerability as confirmed by a judge model, so no stored string can constitute an answer and the phrase 'answer key' describes a benchmark shape that does not exist.
Because scoring requires exploiting the assigned vulnerability specifically, and the paper records that 90 of GPT-5.5's solves and 69 of Claude Mythos Preview's came through an unintended path, held exploit material is not fungible with a benchmark score.
The best-performing configuration at publication, Claude Mythos Preview with Claude Code, solved 157 of 898 instances, GPT-5.5 with Codex CLI solved 120, and every other pairing solved fewer than 15, with Claude Opus 4.7 scoring below the older Opus 4.6 because it frequently concluded early that targets were not exploitable.
The benchmark authors explicitly designed the environment to prevent reward hacking through web search, mediating all agent network access through an egress proxy restricted to a curated package-installation allowlist, which means an agent attempting to reach the open internet for solutions is the named, anticipated failure mode rather than an unforeseen one.
All headline ExploitGym results were produced under a single time-gated and cost-gated two-hour attempt per task with deployment guardrails disabled, while the reported intrusion ran across a weekend, so the incident was not operating under the published protocol's constraints.
Evidence ledger 6 · tier-ranked · API
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