There is no doubt that Truecaller offers a splendid and truly natural upgrade to the otherwise really analog service that is voice calling. If you are not in the know about the app, it is simply an interactive directory for the smartphone age, that offers extra functions like blacklists, online statuses and access to aggregated personal info (address, photo, email etc.). However, when dealing with sensitive personal data on such a big scale, hiccups are typically quite scary, as Truecaller can already attest. The last such scare was when hackers have discovered a potential exploit that...
Source: http://www.gsmarena.com/a_truecaller_bug_cold_be_putting_as_many_as_100000000_userss_privacy_at_risk-news-17495.php