Array#pack method converts the receiver's contents into a string with specified format. If the receiver contains some tainted objects, the returned string also should be tainted. String#unpack method which converts the receiver into an array also should propagate its tainted flag to the objects contained in the returned array. But, with B, b, H and h directives, the tainted flags are not propagated. So, if a script processes unreliable inputs by Array#pack and/or String#unpack with these directives and checks the reliability with tainted flags, the check might be wrong. https://nvd.nist.gov/vuln/detail/CVE-2018-16396
