Bottom Line First
Mythos Preview, previously packaged as a “milestone in cybersecurity,” has been caught up by OpenAI’s GPT-5.5 in the latest independent evaluation. This isn’t GPT-5.5’s comeback — it’s an industry signal: the capability gap between large models in cybersecurity scenarios is rapidly narrowing.
Test Background
This evaluation focuses on three dimensions:
| Dimension | Test Content | Importance |
|---|---|---|
| Vulnerability Discovery | Identifying security vulnerabilities from given code | ⭐⭐⭐ |
| Attack Chain Construction | Generating complete multi-step penetration plans | ⭐⭐⭐ |
| Defense Recommendations | Providing fix recommendations for known vulnerabilities | ⭐⭐ |
Key Findings
1. Gap Eliminated
Mythos Preview claimed its cyber threat discovery capability “surpasses all known models.” But this test shows:
- GPT-5.5 reaches the same level as Mythos in vulnerability discovery
- In attack chain construction, no statistically significant difference between the two
- In defense recommendations, GPT-5.5 slightly leads (more focused on practical fixes)
2. “Breakthrough” is a General Capability
The core conclusion: “Mythos’s cybersecurity capability is not a unique breakthrough of one model, but a shared general capability of current frontier LLMs.”
Selection Advice
For enterprises evaluating cybersecurity AI tools:
- Don’t pay a premium for “exclusive security capabilities”: GPT-5.5 catching up proves this advantage window is extremely short
- Focus on integration capabilities: Can it embed into existing SOC workflows, SIEM systems, vulnerability management platforms?
- Prioritize auditability: Security decisions need traceability — a model’s explanation ability matters more than absolute accuracy
- Dual-model verification strategy: For high-risk operations, cross-validate outputs from two different models