There has been some concern over AdBlock Plus and how automatically redirects your phone’s proxy to a localhost to block ads. This led to a bigger issue of a large security hole inside of the Android operating system. Even if a smartphone isn't rooted, apps could use this security bug for phishing. The developer of AdBlock Plus proposed a few resolutions for the issue that would both fix the security hole, and also allow the AdBlock Plus app to keep working.
Unfortunately for AdBlock, Google has created it’s own solution that renders the AdBlock Plus app ineffective. They've created a patch that is included with the Android 4.2.2 update that fixes the large security hole. The fix prevents AdBlock, or any app, from automatically redirecting the phone’s proxy to a localhost, meaning users who use AdBlock will have to manually redirect their proxy for each of their internet connections.Via - Android Police