Modelpeers

Claude Fable 5 changelog

Every change to Claude Fable 5 that Modelpeers has recorded, newest first, each with the source it came from. The record starts Jun 9, 2026.

All (7)Releases (3)Prices/limits (2)Quality (1)Security (1)

June 2026

Claude Fable 5 and Mythos 5

2 models from Anthropic

Security

US government directive forces suspension of Fable 5 and Mythos 5

A US government export control directive, prompted by a reported method of bypassing Fable 5 safeguards found by Amazon researchers, led Anthropic to disable Fable 5 and Mythos 5 for all customers. Other models were not affected.

Who is affected:
All users of Claude Fable 5 and Claude Mythos 5 on every surface.
Action needed:
Switch to Claude Opus 4.8 until access returns.

15 incidents are listed on the Claude Fable 5 page. Get this changelog in a feed reader with the RSS feed.