The package printf before 0.6.1 are vulnerable to Regular Expression Denial of Service (ReDoS) via the regex string /\%(?:(([\w_.]+))|([1-9]\d*)\$)?([0 +-]*)(*|\d+)?(.)?(*|\d+)?[hlL]?([\%bscdeEfFgGioOuxX])/g in lib/printf.js. The vulnerable regular expression has cubic worst-case time complexity.