The moment a jailbreak-severity score becomes a shipping threshold, you've published the fence.
Anthropic proposed a Cyber Jailbreak Severity framework for Fable this week, scoring jailbreaks by capability gain and how easily they're found. Genuine step, and it walks up to a trap this field fell into once already.
Governance spent a decade producing scores that sat next to the workflow instead of inside it. A severity framework is better, because it's meant to feed a control. That's also where the risk starts.
A score is an assessment. A control is a decision in the execution path. They get conflated the moment a severity tier hardens into a single configurable threshold that decides what ships. Once that threshold exists and is observable, it's a target. A competent adversary probes until they find its edge and tunes attacks to land just under it. A boundary you can publish is a boundary someone can walk around.
CVSS survived being public because a software vuln is a fixed artifact. A jailbreak against a deployed agent isn't fixed. It moves the instant you describe how you're measuring it.
Agents make it sharper. The same jailbreak tier is a non-event against a read-only agent and a breach against one wired into payment rails or identity. Severity is coupled to what the agent is authorized to do once the prompt gets through. So the operative boundary can't live where the model lives. It has to live at the authorization layer: a decision per action, revocable, versioned, that never trusted the model in the first place.
For a 1.0 the rule is clean: keep the severity scale public as shared language, treat any deployed threshold as an operational secret, and put the real containment at execution. No serious buyer should put a frontier model into production on the strength of a severity threshold alone.
Curious where people here land on the assessment-versus-control line, especially for agents with write access to systems that matter.
First comment: Long version: fixgovernance.ai/essays/the-legible-boundary. No signup, no pitch.