Anthropic Proposes CVE-Style Severity Scale to Standardize AI Jailbreak Risk

Anthropic has introduced the Cyber Jailbreak Severity (CJS) scale, a five-tier framework ranging from CJS-0 (informational, no real threat) to CJS-4 (critical, expert-level attack enablement), designed to bring consistency to how AI jailbreak risks are assessed and communicated. The framework was published alongside the release of Claude Fable 5 and is positioned as an industry standard that AI developers and governments can use to discuss jailbreak severity in common terms. Jailbreaks are graded across four dimensions: capability gain, breadth of applicability, ease of weaponization, and discoverability, with severity bands that scale exponentially. Anthropic has also outlined a four-category classifier for cybersecurity use cases, from unconditionally blocked requests like ransomware development to permitted activities like secure coding and incident response. The company has launched a HackerOne bug bounty program for Fable 5 jailbreak submissions and is openly soliciting feedback on the CJS framework, signaling an intent to build a shared industry standard rather than an internal policy.