Up to 600 million Samsung smartphones, including the latest model S6 and S6 Edge flagships, contain a security flaw which could allow hackers to listen to conversations, read texts or view photos on the phones.

The vulnerability, discovered by US security firm NowSecure, lies in the keyboard software, SwiftKey, which comes pre-installed on the latest Samsung smartphones.

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NowSecure found malicious attackers could gain system user access via the keyboard software's language pack update mechanism, which was unencrypted, and then run code on the device to do just about whatever they wanted.

This included accessing the camera, microphone, files including personal photographs, GPS data, and content of voice calls and text messages.