Gemini 3.5 Flash Cyber and gpt-oss-20b don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. gpt-oss-20b shipped 350 days before Gemini 3.5 Flash Cyber, so benchmark comparisons should account for the intervening progress.

Gemini 3.5 Flash Cyber is proprietary, while gpt-oss-20b is open weight.

Direct benchmark comparisons are unavailable — Gemini 3.5 Flash Cyber and gpt-oss-20b don't publish scores on any of the same benchmarks.