A hacker claims to have stolen personal data—including phone numbers, government IDs, and names—from almost 1 billion Chinese citizens in one of the largest data leaks ever, according to several news reports. The enormous data theft occurred because of a glaring error in a Shanghai police database, The Wall Street Journal and other outlets reported this week. A dashboard allowing anyone to access the data without requiring a password was exposed online for more than a year, up for anyone’s taking. The police database storing private citizens’ information could be freely accessed online anytime between April 2021 and June this...