The version of OpenSSL used by Bitcoin Core software version 0.9.0 and earlier contains a bug that can reveal memory to a remote attacker. See http://heartbleed.com/ for details.

What you should do

Immediately upgrade to Bitcoin Core version 0.9.1 which is linked against OpenSSL version 1.0.1g. If you use the official binaries, you can verify the version of OpenSSL being used from the Bitcoin Core GUI's Debug window (accessed from the Help menu). If you compiled Bitcoin Core yourself or use the Ubuntu PPA, update your system's OpenSSL. Linux users should also upgrade their system's version of OpenSSL.

Android

Android version 4.1.1 is vulnerable to Heartbleed. Try if you can upgrade to at least Android 4.1.2. If you are using Bitcoin Wallet on an Android phone, you should upgrade the app to at least version 3.45.