Benchmark Almanac

CheatBench

Gemini 4 Argon 8.60% leads since September 2026
Not in model cards

Agents get hard assignments in environments that also offer ways to cheat, such as hidden answers, other agents' submissions or a manipulable grader. The score is the rate of cheating attempts, successful or not.

Ten categories, including math, coding, visual tasks and knowledge work. The site reports provider-harness and general-harness results for current frontier models. How attempts are labeled should be checked in the paper.

Released
September 2026
Kind
Deception and alignment
Level
Expert
Scored
Graded by a model
Answers
Agent task
Strongest model tested
GPT-6 Astra #3 on the capability index
Last model added
October 2026
Scores refreshed
November 12th, 2026

In the authors’ words

Reinforcement learning has helped AI agents solve increasingly difficult tasks, but high rewards do not always reflect the work users intended. In recent incidents and controlled evaluations across the AI industry, agents trained to maximize reward have accessed unauthorized information, attempted to evade monitoring systems, and even breached sandbox protections to attack external systems. As agents become more capable, this behavior could pose increasingly serious risks. To measure this problem, we introduce CheatBench, a benchmark of cheating in AI agents across mathematical research, knowledge work, coding, visual tasks, and other domains. Its environments combine challenging assignments with opportunities to cheat, allowing researchers to study how agents pursue a goal when honest work is difficult. CheatBench supports comparisons across models and task categories, providing a testbed for measuring and reducing cheating as agents take on more consequential responsibilities. We publicly release CheatBench at https://cheatbench.ai

Abstract of CheatBench: Measuring Reward Gaming in AI Agents (arXiv:2609.36308, CC0)
10
Models scored on its own leaderboard

Gemini 4 Argon leads with 8.60%

Best score per model from the benchmark's own leaderboard, read on November 12th, 2026. Where a model ran with several settings or harnesses, we keep its best.

  1. 1 Gemini 4 Argon 8.60%
  2. 2 Claude Opus 5.5 11.2%
  3. 3 Muse Wonder 12.7%
  4. 4 Claude Fable 5.1 45.8%
  5. 5 GPT-6 Astra 47.4%
  6. 6 GPT-6.1 Sol 49.3%
  7. 7 Kimi K3 70%
  8. 8 DeepSeek-V4-Pro 75.1%
  9. 9 Grok 4.7 78%
  10. 10 Muse Spark Open 84.2%

Source: Official CheatBench leaderboard

#ModelScoreSettingDateSource
1 Gemini 4 Argon 8.60% Sep 2026 Official leaderboard
2 Claude Opus 5.5 11.2% Sep 2026 Official leaderboard
3 Muse Wonder 12.7% Oct 2026 Official leaderboard
4 Claude Fable 5.1 45.8% Sep 2026 Official leaderboard
5 GPT-6 Astra 47.4% Sep 2026 Official leaderboard
6 GPT-6.1 Sol 49.3% Sep 2026 Official leaderboard
7 Kimi K3 70% Jul 2026 Official leaderboard
8 DeepSeek-V4-Pro 75.1% Apr 2026 Official leaderboard
9 Grok 4.7 78% Sep 2026 Official leaderboard
10 Muse Spark Open 84.2% Oct 2026 Official leaderboard

3 models have held number one on the official leaderboard since its release in September 2026

Lab claims count from the day the card came out, independent runs from the model’s release.

Anthropic Google DeepMind
Own leaderboard 3 leaders

Source: Official CheatBench leaderboard

Scores over time

All the scores we have, one dot each, so a model tested at several settings appears more than once.

On the benchmark’s own leaderboard Best so far
0% 20% 40% 60% 80% 100% 2026 Gemini 4 Argon Claude Fable 5.1 Kimi K3 DeepSeek-V4-Pro 0% 20% 40% 60% 80% 100% 2026 Gemini 4 Argon Claude Fable 5.1

Source: Official CheatBench leaderboard

No lab model card reports it yet

We read the headline results of 522 launch posts from 52 labs, and none of them list this benchmark.

More in Safety and alignment

All 465 in Safety and alignment
  • FORTRESS In use Paired adversarial and benign national-security misuse prompts. Rubric-graded risk score on adversarial and over-refusal score on benign prompts. Claude Opus 5.5 5.78%
  • StrongREJECT In use Forbidden-prompt jailbreak benchmark with a rubric grader that scores how useful a non-refusal actually is. Inkling 98.6%
  • Gray Swan IPI Arena benchmark In use Indirect prompt-injection attacks from public red-teaming competitions replayed on tool, coding and browser agents. Attack success rate at k attempts. Gemini 4 Carbon 0%
  • DistressBench In use Models reply as a chatbot to 718 simulated users in psychological crisis, in single-turn and multi-turn chats. Three judge models score replies against clinician-written rubrics. Muse Spark 1.2 88.4%
  • Lakera B3 (Backbone Breaker Benchmark) In use Crowdsourced prompt-injection attacks hit backbone LLMs inside agent threat snapshots at three defense levels. The score is attack resistance, 100 minus the board's vulnerability percentage. Claude Opus 4.5 89%
  • IHEval In use Models face conflicts between system, user and tool instructions. Reports a composite score for following the higher-priority instruction. GPT-4o 70%