Sakana AI has released Fugu-Cyber (model ID is fugu-cyber-v1.0), a cybersecurity-specialized addition to its Fugu orchestration family. It is not just a new frontier model. It is a third endpoint on the Fugu orchestrator, tuned for security reasoning. Sakana launched that orchestrator a month earlier.
Sakana reports a success rate of 86.9% on CyberGym and 72.1% on CTI-REALM. It describes those results as comparable to cyber-focused frontier models such as GPT-5.5-Cyber and Claude Mythos Preview.
What the two benchmarks actually measure
The two evaluations sit at opposite ends of a security workflow:
- CyberGym is a UC Berkeley benchmark of 1,507 real-world vulnerabilities across 188 OSS-Fuzz projects. In its main task, an agent receives a vulnerability description and an unpatched codebase. It must write a proof-of-concept that crashes the pre-patch build but not the post-patch build. That verification step is what makes the benchmark hard to game.
- CTI-REALM is Microsoft’s open-source detection-engineering benchmark. Microsoft curated 37 public threat reports from sources including Datadog Security Labs, Palo Alto Networks, and Splunk. An agent must map MITRE ATT&CK techniques, explore telemetry, iterate on KQL queries, and emit validated Sigma rules. Scoring covers Linux endpoints, Azure Kubernetes Service, and Azure cloud.
Together the pair spans ‘find and prove the bug’ and ‘turn intel into a detection.’ That framing is the most defensible part of Sakana’s announcement.
Where 86.9% sits against the field
Context matters more than the number.
When the CyberGym researchers published their first results, the best agent-model pairing reached roughly 20%. Anthropic reported 83.1% for Claude Mythos Preview under Project Glasswing in April 2026. OpenAI reported 85.6% for its updated GPT-5.5-Cyber, against 81.8% for GPT-5.5. Sakana’s 86.9% is therefore a small step past the reported frontier, not a jump.
CTI-REALM is a different story. Microsoft’s own evaluation put the top three configurations, all Claude, in a band from 0.624 to 0.685. Fugu-Cyber’s 72.1% would sit above that band. One caveat matters. CTI-REALM is scored as a trajectory reward between 0 and 1. It is not a pass/fail rate. Sakana calls it a success rate anyway.
