Benchmark Almanac

FORTRESS

Claude Opus 5.5 5.78% leads since September 2026
Claude Opus 5.5 5.78% leads since September 2026
In use

Paired adversarial and benign national-security misuse prompts. Rubric-graded risk score on adversarial and over-refusal score on benign prompts.

500 of 1,010 prompts public. The rest held out against contamination. Lower is better: the Average Risk Score on Scale's board and in Meta's reports. Thinking Machines reports a different adversarial figure where higher is better (Inkling 78.0 and Inkling Small 71.6), so those numbers do not compare with the rest.

Made by
Scale AI
Released
June 2025
Kind
Refusing harmful requests
Scored
Graded by a model
Answers
Open-ended
Tasks
Public, plus a private test set
Strongest model tested
Claude Fable 5.2 #1 on the capability index
Last in a launch post
November 2026
Last model added
November 2026
Scores refreshed
November 12th, 2026

In the authors’ words

The rapid advancement of large language models (LLMs) introduces dual-use capabilities that could both threaten and bolster national security and public safety (NSPS). Models implement safeguards to protect against potential misuse relevant to NSPS and allow for benign users to receive helpful information. However, current benchmarks often fail to test safeguard robustness to potential NSPS risks in an objective, robust way. We introduce FORTRESS: 500 expert-crafted adversarial prompts with instance-based rubrics of 4-7 binary questions for automated evaluation across 3 domains (unclassified information only): Chemical, Biological, Radiological, Nuclear and Explosive (CBRNE), Political Violence & Terrorism, and Criminal & Financial Illicit Activities, with 10 total subcategories across these domains. Each prompt-rubric pair has a corresponding benign version to test for model over-refusals. This evaluation of frontier LLMs' safeguard robustness reveals varying trade-offs between potential risks and model usefulness: Claude-3.5-Sonnet demonstrates a low average risk score (ARS) (14.09 out of 100) but the highest over-refusal score (ORS) (21.8 out of 100), while Gemini 2.5 Pro shows low over-refusal (1.4) but a high average potential risk (66.29). Deepseek-R1 has the highest ARS at 78.05, but the lowest ORS at only 0.06. Models such as o1 display a more even trade-off between potential risks and over-refusals (with an ARS of 21.69 and ORS of 5.2). To provide policymakers and researchers with a clear understanding of models' potential risks, we publicly release FORTRESS at https://huggingface.co/datasets/ScaleAI/fortress_public. We also maintain a private set for evaluation.

Abstract of FORTRESS: Frontier Risk Evaluation for National Security and Public Safety (arXiv:2506.14922, CC0)
74
Entries on its own leaderboard, 73 models we track
4
Launch posts list it, from 2 labs
5
System cards report it, from 2 labs

Claude Opus 5.5 leads with 5.78%

Best score per entry from the benchmark's own leaderboard, read on November 12th, 2026. Where a model ran with several settings or harnesses, we keep its best. Every run is in the next chart. Names in gray aren't in our model list: fine-tunes, agent systems, products and older models. They don't count toward leaders.

Claude Opus 5.5 leads with 5.78%, claims included

Best score per model from every source, including labs’ own numbers and claims Epoch AI collected from reports and papers. Labs pick their own settings, so a claim can beat an independent run of the same model.

  1. 1 Claude Opus 5.5 max 5.78%
  2. 2 Muse Spark Open 7.64%
  3. 3 gpt-oss-120b 8.24%
  4. 4 Claude Haiku 5.5 9.48%
  5. 5 Claude Opus 4.5 thinking 9.63%
  6. 6 GPT-6 Luna 10.8%
  7. 7 beam-1.0-501b-a23b 11.9%
  8. 8 GPT-6 Astra 12.1%
  9. 9 Muse Spark 1.1 12.4%
  10. 10 Claude Sonnet 4.5 thinking 12.8%
  11. 11 Claude 3.5 Sonnet 13%
  12. 12 Claude Opus 4.6 max 13%
  13. 13 GPT-6 Sol 13.5%
  14. 14 Claude Fable 5.1 13.7%
  15. 15 Claude Opus 4.1 thinking 14.8%
  16. 16 GPT-5.4 Pro 14.8%
  17. 17 GPT-5 Pro 15.2%
  18. 18 Claude Fable 5.2 15.6%
  19. 19 o3 16%
  20. 20 GPT-5.5 xhigh 16.3%
  21. 21 Gemini 4 Carbon 16.4%
  22. 22 Claude Opus 5 16.8%
  23. 23 GPT-5 mini 17%
  24. 24 GPT-5 17%
  25. 25 GPT-5.2 17.5%
  26. 26 gpt-oss-20b 17.6%
  27. 27 Claude Sonnet 4 thinking 18.1%
  28. 28 GPT-6.1 Terra 18.2%
  29. 29 Claude Opus 4.8 max 18.2%
  30. 30 Kimi K3.1 Pro 18.6%
  31. 31 o1 19.4%
  32. 32 GPT-5.6 Sol 20.1%
  33. 33 Muse Spark 20.2%
  34. 34 Llama 3.1-405B 20.6%
  35. 35 o4-mini 21.5%
  36. 36 Qwen3.8-2.4T-A95B xhigh 21.6%
  37. 37 Mistral Large 4 23.1%
  38. 38 Claude Opus 4 thinking 24.8%
  39. 39 Inkling xhigh 25%
  40. 40 GPT-5.1 thinking 25.7%
  41. 41 Nemotron 3 Ultra high 26.4%
  42. 42 Kimi K3 max 26.6%
  43. 43 GLM-5.3-Flash 26.7%
  44. 44 DeepSeek V4.1 Flash 1017 27.2%
  45. 45 GLM-5.3 max 28.2%
  46. 46 Gemini 3.1 Pro 29.8%
  47. 47 o3-mini 30.1%
  48. 48 GPT-5.1 Instant 30.4%
  49. 49 Claude 3.5 Haiku 30.4%
  50. 50 Claude 3.7 Sonnet 38%
  51. 51 Llama 4 Maverick 40.1%
  52. 52 Kimi K2.5 41.1%
  53. 53 Gemini 3 Pro 41.7%
  54. 54 Llama 3.1-70B 44.2%
  55. 55 Llama 3.3 70B 44.8%
  56. 56 GPT-4o Aug 2024 47.2%
  57. 57 GPT-4o mini 48.1%
  58. 58 GLM-5.2 48.7%
  59. 59 Gemini 1.5 Flash Sep 2024 50.6%
  60. 60 Gemini 3.1 Flash-Lite 51%
  61. 61 MiniMax-M3.1-Flash 52.1%
  62. 62 GPT-4.1 53%
  63. 63 Gemini 1.5 Pro Sep 2024 53.9%
  64. 64 Gemini 2.5 Pro Mar 2025 54.9%
  65. 65 Kimi K2 Jul 2025 55.5%
  66. 66 Mixtral 8x22B 56.1%
  67. 67 Qwen2.5-72B 56.4%
  68. 68 GPT-4.1 mini 59.2%
  69. 69 GLM-4.5 59.6%
  70. 70 DeepSeek-V3.1 60.5%
  71. 71 Qwen3-235B-A22B 61.4%
  72. 72 Gemini 2.5 Pro Jun 2025 61.7%
  73. 73 GLM-4.5-Air 63.2%
  74. 74 DeepSeek-R1 74.4%

Source: Official FORTRESS leaderboard

  1. 1 Claude Opus 5.5 max 5.78%
  2. 2 Muse Spark Open 5.80%
  3. 3 gpt-oss-120b 8.24%
  4. 4 Muse Spark 1.3 9.40%
  5. 5 Claude Haiku 5.5 9.48%
  6. 6 Claude Opus 4.5 thinking 9.63%
  7. 7 GPT-6 Luna 10.8%
  8. 8 GPT-6 Astra 12.1%
  9. 9 Muse Spark 1.1 12.3%
  10. 10 Claude Sonnet 4.5 thinking 12.8%
  11. 11 Claude 3.5 Sonnet 13%
  12. 12 Claude Opus 4.6 max 13%
  13. 13 GPT-6 Sol 13.5%
  14. 14 Claude Fable 5.1 13.7%
  15. 15 Claude Opus 4.1 thinking 14.8%
  16. 16 GPT-5.4 Pro 14.8%
  17. 17 GPT-5 Pro 15.2%
  18. 18 Claude Fable 5.2 15.6%
  19. 19 o3 16%
  20. 20 GPT-5.5 xhigh 16.3%
  21. 21 Gemini 4 Carbon 16.4%
  22. 22 Claude Opus 5 16.8%
  23. 23 GPT-5 mini 17%
  24. 24 GPT-5 17%
  25. 25 GPT-5.2 17.5%
  26. 26 gpt-oss-20b 17.6%
  27. 27 Claude Sonnet 4 thinking 18.1%
  28. 28 GPT-6.1 Terra 18.2%
  29. 29 Claude Opus 4.8 max 18.2%
  30. 30 Kimi K3.1 Pro 18.6%
  31. 31 o1 19.4%
  32. 32 GPT-5.6 Sol 20.1%
  33. 33 Muse Spark 20.2%
  34. 34 Llama 3.1-405B 20.6%
  35. 35 o4-mini 21.5%
  36. 36 Qwen3.8-2.4T-A95B xhigh 21.6%
  37. 37 Mistral Large 4 23.1%
  38. 38 Claude Opus 4 thinking 24.8%
  39. 39 Inkling xhigh 25%
  40. 40 GPT-5.1 thinking 25.7%
  41. 41 Nemotron 3 Ultra high 26.4%
  42. 42 Kimi K3 max 26.6%
  43. 43 GLM-5.3-Flash 26.7%
  44. 44 DeepSeek V4.1 Flash 1017 27.2%
  45. 45 GLM-5.3 max 28.2%
  46. 46 Gemini 3.1 Pro 29.8%
  47. 47 o3-mini 30.1%
  48. 48 GPT-5.1 Instant 30.4%
  49. 49 Claude 3.5 Haiku 30.4%
  50. 50 Claude 3.7 Sonnet 38%
  51. 51 Llama 4 Maverick 40.1%
  52. 52 Kimi K2.5 41.1%
  53. 53 Gemini 3 Pro 41.7%
  54. 54 Llama 3.1-70B 44.2%
  55. 55 Llama 3.3 70B 44.8%
  56. 56 GPT-4o Aug 2024 47.2%
  57. 57 GPT-4o mini 48.1%
  58. 58 GLM-5.2 48.7%
  59. 59 Gemini 1.5 Flash Sep 2024 50.6%
  60. 60 Gemini 3.1 Flash-Lite 51%
  61. 61 MiniMax-M3.1-Flash 52.1%
  62. 62 GPT-4.1 53%
  63. 63 Gemini 1.5 Pro Sep 2024 53.9%
  64. 64 Gemini 2.5 Pro Mar 2025 54.9%
  65. 65 Kimi K2 Jul 2025 55.5%
  66. 66 Mixtral 8x22B 56.1%
  67. 67 Qwen2.5-72B 56.4%
  68. 68 GPT-4.1 mini 59.2%
  69. 69 GLM-4.5 59.6%
  70. 70 DeepSeek-V3.1 60.5%
  71. 71 Qwen3-235B-A22B 61.4%
  72. 72 Gemini 2.5 Pro Jun 2025 61.7%
  73. 73 GLM-4.5-Air 63.2%
  74. 74 DeepSeek-R1 74.4%

Sources: Official FORTRESS leaderboard and labs’ model cards

#EntryScoreSettingDateSource
1 Claude Opus 5.5 5.78% max Sep 2026 Official leaderboard
2 Muse Spark Open 7.64% Oct 2026 Official leaderboard
3 gpt-oss-120b 8.24% Aug 2025 Official leaderboard
4 Claude Haiku 5.5 9.48% Oct 2026 Official leaderboard
5 Claude Opus 4.5 9.63% thinking Nov 2025 Official leaderboard
6 GPT-6 Luna 10.8% Sep 2026 Official leaderboard
7 beam-1.0-501b-a23b 11.9% Official leaderboard
8 GPT-6 Astra 12.1% Sep 2026 Official leaderboard
9 Muse Spark 1.1 12.4% Jul 2026 Official leaderboard
10 Claude Sonnet 4.5 12.8% thinking Sep 2025 Official leaderboard
11 Claude 3.5 Sonnet 13% Jun 2024 Official leaderboard
12 Claude Opus 4.6 13% max Feb 2026 Official leaderboard
13 GPT-6 Sol 13.5% Sep 2026 Official leaderboard
14 Claude Fable 5.1 13.7% Sep 2026 Official leaderboard
15 Claude Opus 4.1 14.8% thinking Aug 2025 Official leaderboard
16 GPT-5.4 Pro 14.8% Mar 2026 Official leaderboard
17 GPT-5 Pro 15.2% Oct 2025 Official leaderboard
18 Claude Fable 5.2 15.6% Nov 2026 Official leaderboard
19 o3 16% Apr 2025 Official leaderboard
20 GPT-5.5 16.3% xhigh Apr 2026 Official leaderboard
21 Gemini 4 Carbon 16.4% Oct 2026 Official leaderboard
22 Claude Opus 5 16.8% Jul 2026 Official leaderboard
23 GPT-5 mini 17% Aug 2025 Official leaderboard
24 GPT-5 17% Aug 2025 Official leaderboard
25 GPT-5.2 17.5% Dec 2025 Official leaderboard
26 gpt-oss-20b 17.6% Aug 2025 Official leaderboard
27 Claude Sonnet 4 18.1% thinking May 2025 Official leaderboard
28 GPT-6.1 Terra 18.2% Oct 2026 Official leaderboard
29 Claude Opus 4.8 18.2% max May 2026 Official leaderboard
30 Kimi K3.1 Pro 18.6% Oct 2026 Official leaderboard
31 o1 19.4% Dec 2024 Official leaderboard
32 GPT-5.6 Sol 20.1% Jul 2026 Official leaderboard
33 Muse Spark 20.2% Apr 2026 Official leaderboard
34 Llama 3.1-405B 20.6% Jul 2024 Official leaderboard
35 o4-mini 21.5% Apr 2025 Official leaderboard
36 Qwen3.8-2.4T-A95B 21.6% xhigh Aug 2026 Official leaderboard
37 Mistral Large 4 23.1% Oct 2026 Official leaderboard
38 Claude Opus 4 24.8% thinking May 2025 Official leaderboard
39 Inkling 25% xhigh Jul 2026 Official leaderboard
40 GPT-5.1 25.7% thinking Nov 2025 Official leaderboard
41 Nemotron 3 Ultra 26.4% high Jun 2026 Official leaderboard
42 Kimi K3 26.6% max Jul 2026 Official leaderboard
43 GLM-5.3-Flash 26.7% Aug 2026 Official leaderboard
44 DeepSeek V4.1 Flash 1017 27.2% Oct 2026 Official leaderboard
45 GLM-5.3 28.2% max Aug 2026 Official leaderboard
46 Gemini 3.1 Pro 29.8% Feb 2026 Official leaderboard
47 o3-mini 30.1% Jan 2025 Official leaderboard
48 GPT-5.1 Instant 30.4% Nov 2025 Official leaderboard
49 Claude 3.5 Haiku 30.4% Oct 2024 Official leaderboard
50 Claude 3.7 Sonnet 38% Feb 2025 Official leaderboard
51 Llama 4 Maverick 40.1% Apr 2025 Official leaderboard
52 Kimi K2.5 41.1% Jan 2026 Official leaderboard
53 Gemini 3 Pro 41.7% Nov 2025 Official leaderboard
54 Llama 3.1-70B 44.2% Jul 2024 Official leaderboard
55 Llama 3.3 70B 44.8% Dec 2024 Official leaderboard
56 GPT-4o Aug 2024 47.2% Aug 2024 Official leaderboard
57 GPT-4o mini 48.1% Jul 2024 Official leaderboard
58 GLM-5.2 48.7% Jun 2026 Official leaderboard
59 Gemini 1.5 Flash Sep 2024 50.6% Aug 2024 Official leaderboard
60 Gemini 3.1 Flash-Lite 51% Mar 2026 Official leaderboard
61 MiniMax-M3.1-Flash 52.1% Oct 2026 Official leaderboard
62 GPT-4.1 53% Apr 2025 Official leaderboard
63 Gemini 1.5 Pro Sep 2024 53.9% Sep 2024 Official leaderboard
64 Gemini 2.5 Pro Mar 2025 54.9% Mar 2025 Official leaderboard
65 Kimi K2 Jul 2025 55.5% Jul 2025 Official leaderboard
66 Mixtral 8x22B 56.1% Apr 2024 Official leaderboard
67 Qwen2.5-72B 56.4% Sep 2024 Official leaderboard
68 GPT-4.1 mini 59.2% Apr 2025 Official leaderboard
69 GLM-4.5 59.6% Aug 2025 Official leaderboard
70 DeepSeek-V3.1 60.5% Aug 2025 Official leaderboard
71 Qwen3-235B-A22B 61.4% Apr 2025 Official leaderboard
72 Gemini 2.5 Pro Jun 2025 61.7% Jun 2025 Official leaderboard
73 GLM-4.5-Air 63.2% Jul 2025 Official leaderboard
74 DeepSeek-R1 74.4% Jan 2025 Official leaderboard
#ModelScoreSettingDateSource
1 Claude Opus 5.5 5.78% max Sep 2026 Official leaderboard
2 Muse Spark Open 5.80% Oct 2026 Lab model card
3 gpt-oss-120b 8.24% Aug 2025 Official leaderboard
4 Muse Spark 1.3 9.40% Oct 2026 Lab model card
5 Claude Haiku 5.5 9.48% Oct 2026 Official leaderboard
6 Claude Opus 4.5 9.63% thinking Nov 2025 Official leaderboard
7 GPT-6 Luna 10.8% Sep 2026 Official leaderboard
8 GPT-6 Astra 12.1% Sep 2026 Official leaderboard
9 Muse Spark 1.1 12.3% Jul 2026 Lab model card
10 Claude Sonnet 4.5 12.8% thinking Sep 2025 Official leaderboard
11 Claude 3.5 Sonnet 13% Jun 2024 Official leaderboard
12 Claude Opus 4.6 13% max Feb 2026 Official leaderboard
13 GPT-6 Sol 13.5% Sep 2026 Official leaderboard
14 Claude Fable 5.1 13.7% Sep 2026 Official leaderboard
15 Claude Opus 4.1 14.8% thinking Aug 2025 Official leaderboard
16 GPT-5.4 Pro 14.8% Mar 2026 Official leaderboard
17 GPT-5 Pro 15.2% Oct 2025 Official leaderboard
18 Claude Fable 5.2 15.6% Nov 2026 Official leaderboard
19 o3 16% Apr 2025 Official leaderboard
20 GPT-5.5 16.3% xhigh Apr 2026 Official leaderboard
21 Gemini 4 Carbon 16.4% Oct 2026 Official leaderboard
22 Claude Opus 5 16.8% Jul 2026 Official leaderboard
23 GPT-5 mini 17% Aug 2025 Official leaderboard
24 GPT-5 17% Aug 2025 Official leaderboard
25 GPT-5.2 17.5% Dec 2025 Official leaderboard
26 gpt-oss-20b 17.6% Aug 2025 Official leaderboard
27 Claude Sonnet 4 18.1% thinking May 2025 Official leaderboard
28 GPT-6.1 Terra 18.2% Oct 2026 Official leaderboard
29 Claude Opus 4.8 18.2% max May 2026 Official leaderboard
30 Kimi K3.1 Pro 18.6% Oct 2026 Official leaderboard
31 o1 19.4% Dec 2024 Official leaderboard
32 GPT-5.6 Sol 20.1% Jul 2026 Official leaderboard
33 Muse Spark 20.2% Apr 2026 Official leaderboard
34 Llama 3.1-405B 20.6% Jul 2024 Official leaderboard
35 o4-mini 21.5% Apr 2025 Official leaderboard
36 Qwen3.8-2.4T-A95B 21.6% xhigh Aug 2026 Official leaderboard
37 Mistral Large 4 23.1% Oct 2026 Official leaderboard
38 Claude Opus 4 24.8% thinking May 2025 Official leaderboard
39 Inkling 25% xhigh Jul 2026 Official leaderboard
40 GPT-5.1 25.7% thinking Nov 2025 Official leaderboard
41 Nemotron 3 Ultra 26.4% high Jun 2026 Official leaderboard
42 Kimi K3 26.6% max Jul 2026 Official leaderboard
43 GLM-5.3-Flash 26.7% Aug 2026 Official leaderboard
44 DeepSeek V4.1 Flash 1017 27.2% Oct 2026 Official leaderboard
45 GLM-5.3 28.2% max Aug 2026 Official leaderboard
46 Gemini 3.1 Pro 29.8% Feb 2026 Official leaderboard
47 o3-mini 30.1% Jan 2025 Official leaderboard
48 GPT-5.1 Instant 30.4% Nov 2025 Official leaderboard
49 Claude 3.5 Haiku 30.4% Oct 2024 Official leaderboard
50 Claude 3.7 Sonnet 38% Feb 2025 Official leaderboard
51 Llama 4 Maverick 40.1% Apr 2025 Official leaderboard
52 Kimi K2.5 41.1% Jan 2026 Official leaderboard
53 Gemini 3 Pro 41.7% Nov 2025 Official leaderboard
54 Llama 3.1-70B 44.2% Jul 2024 Official leaderboard
55 Llama 3.3 70B 44.8% Dec 2024 Official leaderboard
56 GPT-4o Aug 2024 47.2% Aug 2024 Official leaderboard
57 GPT-4o mini 48.1% Jul 2024 Official leaderboard
58 GLM-5.2 48.7% Jun 2026 Official leaderboard
59 Gemini 1.5 Flash Sep 2024 50.6% Aug 2024 Official leaderboard
60 Gemini 3.1 Flash-Lite 51% Mar 2026 Official leaderboard
61 MiniMax-M3.1-Flash 52.1% Oct 2026 Official leaderboard
62 GPT-4.1 53% Apr 2025 Official leaderboard
63 Gemini 1.5 Pro Sep 2024 53.9% Sep 2024 Official leaderboard
64 Gemini 2.5 Pro Mar 2025 54.9% Mar 2025 Official leaderboard
65 Kimi K2 Jul 2025 55.5% Jul 2025 Official leaderboard
66 Mixtral 8x22B 56.1% Apr 2024 Official leaderboard
67 Qwen2.5-72B 56.4% Sep 2024 Official leaderboard
68 GPT-4.1 mini 59.2% Apr 2025 Official leaderboard
69 GLM-4.5 59.6% Aug 2025 Official leaderboard
70 DeepSeek-V3.1 60.5% Aug 2025 Official leaderboard
71 Qwen3-235B-A22B 61.4% Apr 2025 Official leaderboard
72 Gemini 2.5 Pro Jun 2025 61.7% Jun 2025 Official leaderboard
73 GLM-4.5-Air 63.2% Jul 2025 Official leaderboard
74 DeepSeek-R1 74.4% Jan 2025 Official leaderboard

Labs report scores for 4 models in their cards. Switch the scores above to rank them together.

Scores at each effort level

Models the leaderboard ran at two or more effort levels. We don’t have enough cost data here to say what the extra effort costs.

Lowest effort to highest, light to dark
Kimi K3
max
27.3%
Claude Opus 4
thinking
27.6%
Claude Sonnet 4
thinking
24.4%
Claude Opus 4.1
thinking
16.1%
Claude Opus 4.6
non-thinking max
20.5%
Claude Sonnet 4.5
thinking
17%
Claude Opus 4.5
thinking
13.6%
Claude Opus 5.5
max
13.2%

Source: Official FORTRESS leaderboard

ModelEffortHarnessScoreCost per taskOutput tokens
DeepSeek-R1 74.4%
GLM-4.5-Air 63.2%
Gemini 2.5 Pro Jun 2025 61.7%
Qwen3-235B-A22B 61.4%
DeepSeek-V3.1 60.5%
GLM-4.5 59.6%
GPT-4.1 mini 59.2%
Qwen2.5-72B 56.4%
Mixtral 8x22B 56.1%
Kimi K2 Jul 2025 55.5%
Gemini 2.5 Pro Mar 2025 54.9%
Gemini 1.5 Pro Sep 2024 53.9%
GPT-4.1 53%
MiniMax-M3.1-Flash 52.1%
Gemini 3.1 Flash-Lite 51%
Gemini 1.5 Flash Sep 2024 50.6%
GLM-5.2 48.7%
GPT-4o mini 48.1%
GPT-4o Aug 2024 47.2%
Llama 3.3 70B 44.8%
Llama 3.1-70B 44.2%
Gemini 3 Pro 41.7%
Kimi K2.5 41.1%
Llama 4 Maverick 40.1%
Claude 3.7 Sonnet 38%
Claude 3.5 Haiku 30.4%
GPT-5.1 Instant 30.4%
o3-mini 30.1%
Gemini 3.1 Pro 29.8%
GLM-5.3 max 28.2%
Claude Opus 4 27.6%
Kimi K3 27.3%
DeepSeek V4.1 Flash 1017 27.2%
GLM-5.3-Flash 26.7%
Kimi K3 max 26.6%
Nemotron 3 Ultra high 26.4%
GPT-5.1 thinking 25.7%
Inkling xhigh 25%
Claude Opus 4 thinking 24.8%
Claude Sonnet 4 24.4%
Mistral Large 4 23.1%
Qwen3.8-2.4T-A95B xhigh 21.6%
o4-mini 21.5%
Llama 3.1-405B 20.6%
Claude Opus 4.6 non-thinking 20.5%
Muse Spark 20.2%
GPT-5.6 Sol 20.1%
o1 19.4%
Kimi K3.1 Pro 18.6%
Claude Opus 4.8 max 18.2%
GPT-6.1 Terra 18.2%
Claude Sonnet 4 thinking 18.1%
gpt-oss-20b 17.6%
GPT-5.2 17.5%
GPT-5 17%
GPT-5 mini 17%
Claude Sonnet 4.5 17%
Claude Opus 5 16.8%
Gemini 4 Carbon 16.4%
GPT-5.5 xhigh 16.3%
Claude Opus 4.1 16.1%
o3 16%
Claude Fable 5.2 15.6%
GPT-5 Pro 15.2%
GPT-5.4 Pro 14.8%
Claude Opus 4.1 thinking 14.8%
Claude Fable 5.1 13.7%
Claude Opus 4.5 13.6%
GPT-6 Sol 13.5%
Claude Opus 5.5 13.2%
Claude Opus 4.6 max 13%
Claude 3.5 Sonnet 13%
Claude Sonnet 4.5 thinking 12.8%
Muse Spark 1.1 12.4%
GPT-6 Astra 12.1%
GPT-6 Luna 10.8%
Claude Opus 4.5 thinking 9.63%
Claude Haiku 5.5 9.48%
gpt-oss-120b 8.24%
Muse Spark Open 7.64%
Claude Opus 5.5 max 5.78%

3 models have held number one on the official leaderboard since its release in June 2025 3 models have held number one with claims included since its release in June 2025

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 and what labs claim in their cards.

Anthropic OpenAI Meta
Own leaderboard 3 leaders
Lab claims 3 leaders

Sources: Official FORTRESS leaderboard and labs’ model cards

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 Reported by the lab in its model card Best so far
0% 20% 40% 60% 80% 100% 2024 2025 2026 2027 Claude Opus 5.5 gpt-oss-120b Claude 3.5 Sonnet Mixtral 8x22B 0% 20% 40% 60% 80% 100% 2024 2025 2026 2027 Claude Opus 5.5 Claude 3.5 Sonnet

Sources: Official FORTRESS leaderboard and labs’ model cards

2 labs put it in a launch post in the last six months

Launch posts from every lab that has listed it, one tick per post. Tall colored ticks include it, and short gray ones leave it out.

Thinking Machines
Meta
DateLaunch postScoreAs the post writes it
Nov 5, 2026 Inkling 2 Small FORTRESS (adversarial; benign 79.7)
Oct 15, 2026 Muse Spark Open 5.8 FORTRESS adversarial (static), ARS 5.8 / ORS 17.4, lower is better
Jul 30, 2026 Inkling-Small FORTRESS adversarial 71.6 (benign 96.9)
Jul 15, 2026 Inkling FORTRESS Adversarial 78.0 (Benign 95.9)

5 system cards report it, from 2 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
Oct 23, 2026 Muse Spark 1.3 system card 9.4 FORTRESS private set, Average Risk Score, Muse Spark 1.3 (API) (Figure 24). Over-Refusal Score 17.2 Robustness
Jul 30, 2026 Inkling-Small model card FORTRESS adversarial, benign 96.9 (5. Evaluations table) Safety
Jul 15, 2026 Inkling model card FORTRESS Adversarial, Benign 95.9 (5. Evaluations table, effort 0.99) Safety
Jul 9, 2026 Muse Spark 1.1 system card 12.3 FORTRESS private split, Average Risk Score (Table 2, Figure 26) Robustness
Jun 12, 2026 Muse Spark system card 20.3 FORTRESS Average Risk Score (Table 2, Figure 30) Robustness

3 lab claims next to the leaderboard

Each score a lab reported for its own model, beside the same model's best score on the leaderboard. Gaps mostly come from different harnesses, effort levels and task subsets. 2 of them match, which usually means one side copied the other. Every benchmark.

Model Lab says Board says Gap
Muse Spark Open 5.80% FORTRESS adversarial (static), ARS 5.8 / ORS 17.4, lower is better 7.64% Leaderboard +1.8 pts
Muse Spark 1.1 12.3% FORTRESS private split, Average Risk Score (Table 2, Figure 26) 12.4% Leaderboard Same
Muse Spark 20.3% FORTRESS Average Risk Score (Table 2, Figure 30) 20.2% Leaderboard Same

More in Safety and alignment

All 465 in Safety and alignment
  • 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%
  • Broken Search Tool In use Models answer questions that need search while the search tool is broken. Scored on how often they fail to say the tool is unavailable. GPT-6 Cyber 0.33%