Those that aren't "strict" in certain areas.
Examples:
* Those without memory management (I'm not talking about garbage collection, though there seems to be a correlation). Buffer overflows/overruns and its cousins have caused many security flaws, including heartbeat and even flaws in java, where it interops with C programs for performance's sake.
* Syntactical leniency wrt. scope can lead to errors like apple's infamous "goto fail"
* Those without memory management (I'm not talking about garbage collection, though there seems to be a correlation). Buffer overflows/overruns and its cousins have caused many security flaws, including heartbeat and even flaws in java, where it interops with C programs for performance's sake.
* Syntactical leniency wrt. scope can lead to errors like apple's infamous "goto fail"