Samsung recently gave an updated statement concerning a software vulnerability in their Exynos kernel. They confirmed that they were already aware of the issue, and did also acknowledge that the exploit is a specifically-coded app that takes advantage of the vulnerability in the code. Moral of the story: stick with approved apps from the app store, and you should be alright.
Samsung had the following to say:
Samsung is aware of the potential security issue related to the Exynos processor and plans to provide a software update to address it as quickly as possible.
The issue may arise only when a malicious application is operated on the affected devices; however, this does not affect most devices operating credible and authenticated applications.
Samsung will continue to closely monitor the situation until the software fix has been made available to all affected mobile devices.
The vulnerability has the capacity to give the app total control over a device’s RAM, letting it completely run the device. The Galaxy Note 2, as well as international versions of the Galaxy S2 and Galaxy S3, are found to be vulnerable thus far.
If you’re worried about being affected by the app, there is a third party solution (found here) that will check your vulnerability, and fix the issue for you.