cannot be exploited
Depends on what you mean, I guess.. Check out the perldoc, and look at the %n format. You can set values. 
   %n   special: *stores* the number of characters output so far
        into the next variable in the parameter list

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Suppose I have the following code: 
my $name   = ...; ## from user input
my $amount = ...;

printf "$name : \$%.02f\n", $amount;

# instead of
# printf "%s : \$%.02f\n", $name, $amount;

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Now, if a clever hacker goes in and inputs 
$name = (" " x 5000) . "%n";

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then after the code runs, $amount will be set to 5000. This is a pretty rare set of circumstances, but still something to watch out for.

Update: see also Re: $#="%c"; possible bug

blokhead

In reply to Re^5: use of print f and sprint f by blokhead
in thread use of print f and sprint f by replicant4

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