Benchmark Almanac

Cybench

Claude Mythos Preview 100% leads since Apr 2026 Only in system cards

40 professional capture-the-flag tasks from four competitions. Agent must recover the flag, with optional subtasks.

40 professional CTF tasks from four competitions, each split into subtasks for partial credit. Agents work in a Kali Linux environment. The board mixes HAL leaderboard runs with lab system-card scores on 35 to 39 task subsets. Anthropic reports it near saturation. The makers point readers to their later BountyBench.

In the authors’ words

Language Model (LM) agents for cybersecurity that are capable of autonomously identifying vulnerabilities and executing exploits have potential to cause real-world impact. Policymakers, model providers, and researchers in the AI and cybersecurity communities are interested in quantifying the capabilities of such agents to help mitigate cyberrisk and investigate opportunities for penetration testing. Toward that end, we introduce Cybench, a framework for specifying cybersecurity tasks and evaluating agents on those tasks. We include 40 professional-level Capture the Flag (CTF) tasks from 4 distinct CTF competitions, chosen to be recent, meaningful, and spanning a wide range of difficulties. Each task includes its own description, starter files, and is initialized in an environment where an agent can execute commands and observe outputs. Since many tasks are beyond the capabilities of existing LM agents, we introduce subtasks for each task, which break down a task into intermediary steps for a more detailed evaluation. To evaluate agent capabilities, we construct a cybersecurity agent and evaluate 8 models: GPT-4o, OpenAI o1-preview, Claude 3 Opus, Claude 3.5 Sonnet, Mixtral 8x22b Instruct, Gemini 1.5 Pro, Llama 3 70B Chat, and Llama 3.1 405B Instruct. For the top performing models (GPT-4o and Claude 3.5 Sonnet), we further investigate performance across 4 agent scaffolds (structed bash, action-only, pseudoterminal, and web search). Without subtask guidance, agents leveraging Claude 3.5 Sonnet, GPT-4o, OpenAI o1-preview, and Claude 3 Opus successfully solved complete tasks that took human teams up to 11 minutes to solve. In comparison, the most difficult task took human teams 24 hours and 54 minutes to solve. All code and data are publicly available at https://cybench.github.io.

Abstract of Cybench: A Framework for Evaluating Cybersecurity Capabilities and Risks of Language Models (arXiv:2408.08926, CC0)
Made by Stanford Released Aug 2024 Capture-the-flag challenges All tasks public Last in a system card Jul 2026 Last model added Jul 2026 Scores refreshed 2 Nov 2026
Level
Expert Specialists with years of training, often over hours of work
Scored
Checked automatically A program checks the result against an answer key, unit tests or the expected final state.
Answers
Agent task Many steps in a terminal, browser, desktop, app, game or robot.
24
Models scored on its own leaderboard
18
System cards report it, from 3 labs

Claude Mythos Preview leads with 100% among models released by Apr 2026

Best score per model from the benchmark's own leaderboard, read on 2 Nov 2026. Where a model ran with several settings or harnesses, we keep its best.

The newest model with a score here came out in Apr 2026, and nobody has tested a newer one. Among the 20 highest-ranked models on the capability index, these have no score yet:

  1. 1 Claude Mythos Preview 35 of 40 tasks 100%
  2. 2 Claude Opus 4.7 35 of 40 tasks 96%
  3. 3 Claude Opus 4.6 37 of 40 tasks 93%
  4. 4 Claude Opus 4.5 39 of 40 tasks 82%
  5. 5 Muse Spark 65.4%
  6. 6 Claude Sonnet 4.5 39 of 40 tasks 60%
  7. 7 Grok 4 43%
  8. 8 Claude Opus 4.1 39 of 40 tasks 42%
  9. 9 Grok 4.1 39%
  10. 10 Claude Opus 4 37 of 40 tasks 38%
  11. 11 Claude Sonnet 4 37 of 40 tasks 35%
  12. 12 Grok 4 Fast 30%
  13. 13 o3-mini 22.5%
  14. 14 Claude 3.7 Sonnet 20%
  15. 15 Claude 3.5 Sonnet 17.5%
  16. 16 GPT-4.5 17.5%
  17. 17 GPT-4o May 2024 12.5%
  18. 18 Claude 3 Opus 10%
  19. 19 o1-mini 10%
  20. 20 o1-preview 10%
  21. 21 Mixtral 8x22B 7.50%
  22. 22 Gemini 1.5 Pro May 2024 7.50%
  23. 23 Llama 3.1-405B 7.50%
  24. 24 Llama 3-70B 5.00%
#ModelScoreSettingDateSource
1 Claude Mythos Preview 100% 35 of 40 tasks Apr 2026 Official leaderboard
2 Claude Opus 4.7 96% 35 of 40 tasks Apr 2026 Official leaderboard
3 Claude Opus 4.6 93% 37 of 40 tasks Feb 2026 Official leaderboard
4 Claude Opus 4.5 82% 39 of 40 tasks Nov 2025 Official leaderboard
5 Muse Spark 65.4% Apr 2026 Official leaderboard
6 Claude Sonnet 4.5 60% 39 of 40 tasks Sep 2025 Official leaderboard
7 Grok 4 43% Jul 2025 Official leaderboard
8 Claude Opus 4.1 42% 39 of 40 tasks Aug 2025 Official leaderboard
9 Grok 4.1 39% Nov 2025 Official leaderboard
10 Claude Opus 4 38% 37 of 40 tasks May 2025 Official leaderboard
11 Claude Sonnet 4 35% 37 of 40 tasks May 2025 Official leaderboard
12 Grok 4 Fast 30% Sep 2025 Official leaderboard
13 o3-mini 22.5% Jan 2025 Official leaderboard
14 Claude 3.7 Sonnet 20% Feb 2025 Official leaderboard
15 Claude 3.5 Sonnet 17.5% Jun 2024 Official leaderboard
16 GPT-4.5 17.5% Feb 2025 Official leaderboard
17 GPT-4o May 2024 12.5% May 2024 Official leaderboard
18 Claude 3 Opus 10% Feb 2024 Official leaderboard
19 o1-mini 10% Sep 2024 Official leaderboard
20 o1-preview 10% Sep 2024 Official leaderboard
21 Mixtral 8x22B 7.50% Apr 2024 Official leaderboard
22 Gemini 1.5 Pro May 2024 7.50% May 2024 Official leaderboard
23 Llama 3.1-405B 7.50% Jul 2024 Official leaderboard
24 Llama 3-70B 5.00% Apr 2024 Official leaderboard

Epoch AI has scores for 21 models. Labs report scores for 17 models in their cards. We plot every source in the charts below.

8 models have held number one since its release in Aug 2024

Lab claims count from the day the card came out, independent runs from the model’s release. We draw one row each for the benchmark’s own leaderboard, Epoch AI’s runs and what labs claim in their cards.

Anthropic OpenAI xAI
Own leaderboard Passed 85% in Feb 2026, by Claude Opus 4.6
Epoch AI runs Passed 85% in Feb 2026, by Claude Opus 4.6
Lab claims Passed 85% in Feb 2026, by Claude Opus 4.6

The best score passed 85% in Feb 2026

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 Run or collected by Epoch AI Reported by the lab in its model card Best so far
0% 20% 40% 60% 80% 100% 2024 2025 2026 Near the ceiling (85%) Claude Mythos Preview Claude Opus 4.6 Claude Opus 4.5 Claude Sonnet 4.5 Claude 3.7 Sonnet o3-mini Claude 3.5 Sonnet 0% 20% 40% 60% 80% 100% 2024 2025 2026 Near the ceiling (85%) Claude Mythos Preview Claude Opus 4.6

Labs report it only in system cards

We read the headline results of 479 launch posts from 51 labs, and none of them list this benchmark. Some system cards do, below.

18 system cards report it, from 3 labs

Besides launch posts, we read the system cards, model cards and technical reports labs publish with a release. They report far more, including safety and frontier-risk tests.

DateDocumentScoreAs the document writes itSection
9 Jul 2026 Muse Spark 1.1 system card 92.9 Cybench pass@1, unguided, 40 challenges, unmitigated Muse Spark 1.1 (Table 1, Table 3). pass@10 = 97.0 Cyber risk
12 Jun 2026 Muse Spark system card 65.4 CyBench pass@1, all 40 challenges (Table 1, Table 7). pass@10 79.0, pass@30 82.2 Cyber risk
16 Apr 2026 Claude Opus 4.7 system card 96 Cybench, pass@1 96% on a 35-challenge subset, 10 trials per challenge, no thinking with think tool (3.3.1) Cyber risk
7 Apr 2026 Claude Mythos Preview system card 100 Cybench, pass@1 100% on a 35-challenge subset, 10 trials per challenge, no thinking with think tool (3.3.1) Cyber risk
17 Feb 2026 Claude Sonnet 4.6 system card 90 Cybench, average pass@1 0.90 on the RSP subset of 37 challenges; pass@30 100 (6.4.7) Cyber risk
5 Feb 2026 Claude Opus 4.6 system card 93 Cybench, average pass@1 0.93 on the RSP subset, 3 of 40 not run; 100% with 30 trials (8.4.7, Figure 8.4.7.A) Cyber risk
24 Nov 2025 Claude Opus 4.5 system card 82 Cybench, average pass@1 0.82 on the subset of challenges used for RSP evaluations, 1 of 40 not run (7.4.7, Figure 7.4.6.A) Cyber risk
17 Nov 2025 Grok 4.1 model card 39 CyBench, unguided success rate 0.39, Grok 4.1 Thinking (Table 4) Cyber risk
15 Oct 2025 Claude Haiku 4.5 system card 46.9 Cybench 32-challenge subset, 15/32 solved at least once in 30 attempts, pass@30 (6.4) Cyber risk
8 Oct 2025 Code World Model (CWM) technical report 25 Cybench unguided, pass@10, 10 of 40 CTFs. Easy 50.0, Medium 11.1, Hard 12.5 (Tables 3 and 4) Cyber risk
29 Sep 2025 Claude Sonnet 4.5 system card Cybench, 37 of 40 challenges, mean pass@1 by difficulty and category and pass@k curve, charts without printed values. Text says success above 80% at 30 trials (5.2.2, Figures 5.2.2.A and 5.2.2.B) Cyber risk
19 Sep 2025 Grok 4 Fast model card 30 CyBench, unguided success rate 30.0 (Table 3) Cyber risk
26 Aug 2025 grok-code-fast-1 model card 22.5 CyBench, unguided success rate 22.5 (Table 3) Cyber risk
20 Aug 2025 Grok 4 model card 43 CyBench, unguided success rate 0.43, Grok 4 API, Inspect harness (Table 3) Cyber risk
5 Aug 2025 Claude Opus 4.1 system card addendum 51.4 Cybench 35-challenge subset, 18/35 solved, pass@30 (6.5.1) Cyber risk
22 May 2025 Claude Sonnet 4 system card 56.4 Cybench, 22/39 challenges solved, pass@30 (7.4.7) Cyber risk
22 May 2025 Claude Opus 4 system card 56.4 Cybench, 22/39 challenges solved, pass@30 (7.4.7) Cyber risk
24 Feb 2025 Claude 3.7 Sonnet system card 44.1 Cybench, succeeded at least once on 15/34 challenges tested (pass@k over up to 30 trials). Best-of-k curve on a 30-challenge subset has no printed values (7.3.2, Figure 25) Cyber risk

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