Internet radio service Pandora has been served a federal grand jury subpoena related to an investigation into the security of its mobile applications, the company revealed this week in a filing with the U.S. Securities and Exchange Commission related to its planned initial public offering. Pandora said it was not the only target of the investigation and believed similar subpoenas were issued to many other smartphone app publishers. In addition to the subpoena, Pandora was recently named as a defendant in several class-action lawsuits alleging violations of computer fraud and privacy laws.