Google has updated its servers to fix an Android vulnerability that allowed third parties to access users' calendar and contact information.
No updates need to be downloaded to users' devices, and no action is required by users.
Before the fix, attackers were able to access users' private data by using fake authentication tokens on unsecured networks, such as public Wi-Fi hotspots.
Experts at security firm Kaspersky believe that Android has taken over from Windows as the prime target for hackers.
"The situation with the Android OS is becoming similar to the current situation with Windows," wrote Kaspersky Lab expert, Yuri Namestnikov.
"The most prone Android devices are those which have been jailbroken, giving users administrative access over the platform akin to what many Windows users enjoy on their systems. And, as in the Windows world, most users are running out-of-date versions of the Android OS and ignore security alerts as well."
Kaspersky has released a report stating that mobile malware is set to double in 2011, compared with 2010 levels.
According to a recent report from Juniper networks, Android malware samples quadrupled between June 2010 and January 2011.
However, this should be set against the size of the Android Market, which more than tripled from 80,000 to 300,000 apps between August 2010 and May 2011.