A new bug has been disclosed that can affect all Android devices running Ice Cream Sandwich 4.3 or higher. If you download a malicious file, it will disable audio on your device.
The file has to be an infected app or a purposefully-malicious MKV file. When downloaded, a buffer overflow is created for the media server service, resulting in audio no longer working. This can also cause a large amount of RAM to be used, slowing down the device.
Trend-Micro, the creators of the popular Android Antivirus app, actually discovered the bug back in May 2015 and reported it to Google then. Google marked the bug as “low priority”, as this bug can be easily fixed by rebooting the device and deleting either the infected app or MKV file.
The lesson here is pretty much not to download any files or apps from links you don’t trust. Make sure to turn off “unknown” sources under the security settings unless you explicitly are trying to install an app that is unavailable on the Play Store.