Anthropic disclosed that a small group of unauthorized users gained access to its newly released Claude Mythos model on the day the company announced a limited rollout. According to Bloomberg, the intruders guessed the model’s online location using details leaked from a prior breach at data‑training firm Mercur and insider knowledge from a contractor who had evaluated Anthropic’s models. Anthropic said it is investigating the incident and reviewing its monitoring systems, which were designed to log and track model usage. The breach, described by security researchers as a standard “educated guess” attack rather than a sophisticated exploit, did not appear to target the model’s advertised cybersecurity capabilities. The episode raises questions about the robustness of Anthropic’s security controls for a product it has marketed as a “watershed moment” for defending digital infrastructure. Read more →

Anthropic confirmed it is investigating a report that a group gained unauthorized entry to its Claude Mythos model through a third‑party vendor portal. The breach, discovered via internet‑sleuthing tools and a developer portal, appears limited to exploratory testing rather than malicious exploitation. Anthropic’s Claude Mythos, released under the Project Glasswing preview, had been limited to a handful of trusted firms such as Amazon, Microsoft, Apple, Cisco and Mozilla, which used the model to identify hundreds of software flaws. The incident has revived concerns about AI‑driven cyber threats and the company’s recent designation as a supply‑chain risk by the U.S. Department of Defense. Read more →

A small group of users gained entry to Anthropic’s restricted Claude Mythos Preview AI model on the day the company announced its launch, exploiting a third‑party vendor environment by guessing the model’s URL. Anthropic confirmed it is investigating the incident and said there is no evidence the breach affected its core systems. The episode highlights vulnerabilities in the way frontier AI tools are shielded behind external partners, raising concerns about the security of powerful cybersecurity AI models that can autonomously discover and exploit zero‑day vulnerabilities. Read more →