GPT-5.5 matches heavily hyped Mythos Preview in new cybersecurity tests

Last month, Anthropic made a big deal about the supposedly outsize cybersecurity threat represented by its Mythos Preview model, leading the company to restrict the initial release to “critical industry partners.” But new research from the UK's AI Security Institute (AISI) suggests that OpenAI's GPT-5.5, which launched publicly last week , reached "a similar level of performance on our cyber evaluations" as Mythos Preview, which the group evaluated last month . Since 2023, the AISI has run a var