This is the unmodified PoC from the report. The defect was fixed in springboard-ui build 1.0.37391, so against production today the messages are delivered and then rejected by the t.origin !== window.location.origin check — no toast. Full write-up and evidence: the main PoC page.

Victim must be logged in to Anaplan. The page opens the board designer itself, then posts tool calls to it for ~30 s.