Fable 5 Is Back: What Anthropic Learned From Eighteen Days Off The Shelf
TL;DR Fable 5 returns globally on 1 July 2026 on Claude.ai, Claude Code, Claude Cowork, and the Claude Platform, after export controls were lifted on 30 June The recall was triggered by an Amazon research report describing a jailbreak that let Fable 5 identify software vulnerabilities; Anthropic’s testing found Opus 4.8, GPT-5.5, Kimi K2.7, and others could do the same A new safety classifier blocks the specific technique in over 99% of cases; blocked requests fall back to Opus 4.8 Anthropic argues the jailbreak was minor - it intruded into the model’s deliberate “safety margin”, not its core harmful capabilities Together with Amazon, Google, and Microsoft, Anthropic is drafting a shared jailbreak severity framework (capability gain, breadth, ease of weaponisation, discoverability) - the AI equivalent of CVSS Mythos 5 is restored for a set of US Glasswing partners; broader international access remains under government coordination Eighteen days ago I wrote about the government order that pulled Fable 5 and Mythos 5 off the shelf - four days after launch, a verbal export control directive at 5:21pm ET, global suspension for every user including Anthropic’s own staff. The open question in that post was whether access would be restored in days or weeks, and whether the precedent would reshape how every frontier lab ships models. ...