More than half (54 percent) of second-hand mobile phones contain personal data belonging to the original owner, says CPP.
In a study, the fraud protection firm purchased 35 mobile and 50 SIM cards on online auction site eBay. CPP found a total of 247 pieces of data including photos, texts, emails and even banking details on 19 of the mobile phones and 27 of the SIM cards.
Furthermore, half of Brits that purchased a second-hand mobile phone said they found data belonging to the previous owner on the device. However, 81 percent of mobile phone owners claim they wipe their handsets before selling them.
"Many of the security concerns that people think about when they think about their personal computers are applicable in the mobile world," said Joe Nocera, an information security expert with PricewaterhouseCoopers, in a blog.
"As mobile devices become more sophisticated, they lend themselves to the same types of access to email, passwords and other secure information that PCs have done in the past."
CPP mobile data expert Danny Harrison said the report was "a shocking wake-up call" and "shows how mobile phones can inadvertently cause people to be careless with their personal data".
"Consumers are upgrading their mobiles more than ever, and it is imperative people take personal responsibility to properly manage their own data," he added.