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An attacker who can fully or partially control the contents of a format string can crash the Perl interpreter, or cause a denial of service. She can also modify values, perhaps by using the %n|| conversion specifier, and use these values to divert control flow. Their capabilities are not as strong as in C [Seacord 2005]; nonetheless the danger is sufficiently great that the formatted output functions {{sprintf() and printf() should never be passed unsanitized format strings.
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