Pyyan / Compare / GPT-5.6-Cyber vs Claude Opus 5.5
GPT-5.6-Cyber vs Claude Opus 5.5
2 of 5Language Models · verified 24 Sept 2026
GPT-5.6-CyberOpenAIcurrentClaude Opus 5.5Anthropiccurrent
| Specification | GPT-5.6-Cyber | Claude Opus 5.5 |
|---|---|---|
| Summary | Trained to find zero-days and chain exploits. Vetted applicants only. | Fable 5.1's level of work on most tasks, at 40% less to run than Opus 5. |
| Context | 400K | 1M |
| Input ($/Mtok) | Not published | $4 |
| Output ($/Mtok) | Not published | $20 |
| Licence | Proprietary, vetted access | Proprietary |
| Max output | Not published | 128K |
| Parameters | Not published | Not published |
| Released | 10 Aug 2026 | 22 Sep 2026 |
| Model ID | gpt-5.6-cyber | claude-opus-5-5 |
| Category | Language Models | Language Models |
| Official | — | Anthropic ↗ |
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 Opus 5.5
- 66.4% on Terminal-Bench 4.0 against 52.3% for Opus 5, on Anthropic's own harness
- Cache reads cut 60% to $0.20, and output more than 30% faster than Opus 5
- Attempts to work around its boundaries 85% less often than Opus 5, Anthropic reports
Best for agentic coding at flagship quality.