Are Mythos' Cyber Capabilities Overstated? - Yes and No

Published on May 23, 2026 11:32 PM GMT TL;DR: Anthropic restricted access to Claude Mythos Preview, citing a major leap in vulnerability discovery and exploitation capability. I review the 3 most common arguments from skeptics: (1) AISLE Security’s paper showing cheaper models can identify the same bugs as Mythos, (2) benchmark comparisons showing GPT-5.5 performs comparably, and (3) Mythos finding only one low-severity bug in the cURL project. On most cyber capabilities: the skeptics are right.