Pyyan / Compare / GPT-5.6-Cyber vs Claude Fable 5.1
GPT-5.6-Cyber vs Claude Fable 5.1
2 of 5Language Models · verified 2 Sept 2026
GPT-5.6-CyberOpenAIcurrentClaude Fable 5.1Anthropiccurrent
| Specification | GPT-5.6-Cyber | Claude Fable 5.1 |
|---|---|---|
| Summary | Trained to find zero-days and chain exploits. Vetted applicants only. | Same price as Fable 5, and cache reads cost a quarter of what they did. |
| Context | 400K | 1M |
| Input ($/Mtok) | Not published | $10 |
| Output ($/Mtok) | Not published | $50 |
| Licence | Proprietary, vetted access | Proprietary |
| Max output | Not published | 128K |
| Parameters | Not published | Not published |
| Released | 10 Aug 2026 | 1 Sep 2026 |
| Model ID | gpt-5.6-cyber | claude-fable-5-1 |
| Category | Language Models | Language Models |
| Official | — | — |
Highlighted rows are where these differ.
GPT-5.6-Cyber
- Built on GPT-5.6 Sol and trained for finding zero-days and building exploit chains
- Completes 95% of exploit-chain, privilege-escalation and auth-bypass prompts, against 1.5% for Sol
- Reachable only through Daybreak Red, the applicant-vetted tier of OpenAI's defender programme
Best for authorised security research.
Claude Fable 5.1
- Matches or beats Fable 5 at low and medium effort, and pulls clear at high effort
- Cache reads cut to 25% of the old price, so re-reading a long context got much cheaper
- Identical model to Mythos 5.1 underneath; the difference is the safeguards
Best for coding and long-running work.