If the information is confidential business information--that is, information which is not public and to which you only had access due to working there, and which you were supposed to use only for the company's benefit during your employment--then you could be sued by the ex-employer for misappropriation of confidential information. Depending on the exact nature of the information and what consequences its disclosure has for the ex-employer, i.e. how much it costs the ex-employer you could potenially be sued for a great deal of money.