schneier.comarticleGPT-5.5 Vulnerability Detection Eval
Bruce Schneier summarizes a UK AI Security Institute (AISI) evaluation finding that OpenAI's GPT-5.5 performs comparably to Claude Mythos at finding security vulnerabilities, noting GPT-5.5 is generally available while a smaller, cheaper model can achieve similar results with more prompt scaffolding. The post links to AISI's evaluations of both models as evidence for tracking frontier-model offensive/defensive security capability.
TL;DR UK AISI eval finds GPT-5.5 matches Claude Mythos at vulnerability discovery, per Schneier's summary.
Organisations named here
- UK AI Security Institute
Technologies named here
- GPT-5.5
- Claude Mythos
- OpenAI
- Mythos
Techniques named here
- AI-assisted security vulnerability finding
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