A SMS bug that allowed unauthorized Twitter followers to receive protected tweets via SMS or push notifications has been fixed. The bug affected 93,788 Twitter accounts.
Since November 2013, some tweets from protected accounts were accidentally sent to “non-approved” followers. Twitter users who restrict access to their profiles have been contacted by the company alerting them of the issue.
The bug has since been patched and Twitter has “taken steps to protect against this kind of bug in the future.”
Source: Twitter