2026-04-07

Mon, 01 Jan 0001 00:00:00 +0000

Simon Willison — 2026-04-07#

Highlight#

Anthropic’s decision to restrict access to their new Claude Mythos model underscores a massive, sudden shift in AI capabilities. It is a fascinating look at an industry-wide reckoning as open-source maintainers transition from dealing with “AI slop” to facing a tsunami of highly accurate, sophisticated vulnerability reports.

Posts#

[Anthropic’s Project Glasswing - restricting Claude Mythos to security researchers - sounds necessary to me] · Source Anthropic has delayed the general release of Claude Mythos, a general-purpose model similar to Claude Opus 4.6, opting instead to limit access to trusted partners under “Project Glasswing” so they can patch foundational internet systems. Simon digs into the context, tracking how credible security professionals are warning about the ability of frontier LLMs to chain multiple minor vulnerabilities into sophisticated exploits. He even uses git blame to independently verify a 27-year-old OpenBSD kernel bug discovered by the model. He concludes that delaying the release until new safeguards are built, while providing $100M in credits to defenders, is a highly reasonable trade-off.

Simon Willison

Mon, 01 Jan 0001 00:00:00 +0000

Simon Willison — Week of 2026-04-04 to 2026-04-10#

Highlight of the Week#

Anthropic’s decision to delay the general release of their highly capable Claude Mythos model under “Project Glasswing” marks a significant turning point in the AI industry. The move underscores a massive shift in frontier model capabilities, as models evolve from generating text to autonomously chaining multiple minor vulnerabilities into sophisticated exploits, requiring a new level of security safeguards before release.