class SecurityError - Ruby 2.2.4 Core API Reference API Reference

Raised when attempting a potential unsafe operation, typically when the $SAFE level is raised above 0.

foo = "bar"
proc = Proc.new do
  $SAFE = 3
  foo.untaint
end
proc.call

raises the exception:

SecurityError: Insecure: Insecure operation `untaint' at level 3