That's twice in two days. Yesterday, security firm Zvelo discovered a potential exploit against rooted phones. Today, tech blog TheSmartphoneChamp discovered how to accomplish the same feat on non-rooted phones.
While yesterday's exploit required you to crack encrypted files, today's requires you to simply clear the data in the app settings. Doing so forces Google Wallet to reset itself and prompt the user for a new PIN. Once that's done, the attacker ties in a Google PrePaid card to the account and presto—all previously available funds are once again accessible. The method has been tested by multiple sources and confirmed by Google itself.
Google has issued a statement regarding the new method,
We strongly encourage anyone who loses or wants to sell their phone to call Google Wallet support toll-free at 855-492-5538 to disable the prepaid card. We are currently working on an automated fix as well that will be available soon. We also advise all Wallet users to set up a screen lock as an additional layer of protection for their phone.