tech
May 6, 2026
OpenAI isn't far behind Mythos' hacking powers
The head start that cyber defenders were promised when Mythos was unveiled last month is disappearing faster than expected.
TL;DR
- OpenAI's GPT-5.5 model shows nearly equivalent performance to Anthropic's Mythos Preview in finding and exploiting software bugs.
- GPT-5.5 completed a 32-step simulated corporate cyberattack in 2 out of 10 test runs, compared to Mythos' 3 out of 10.
- GPT-5.5 also outperformed Mythos on capture-the-flag tasks testing vulnerability identification, incident reverse-engineering, and web application exploitation.
- The rapid advancement challenges Anthropic's initial estimate of a 6-18 month lead time for similar AI cyber capabilities.
- Access to both Mythos and advanced GPT models is limited to select organizations and vetted cyber defenders.
- The White House has reportedly urged Anthropic to limit Mythos access due to national security concerns.
- OpenAI is providing access to cyber-permissible versions of GPT-5.4 and 5.5 to governments and allies.