Samsung has released a new software update A320FLXXU2CRE3 for Galaxy A3 (2017). The update comes with Android June security patch which addresses Common Vulnerabilities and Exposures (CVE) in the open-source Android OS and additional patches designed specifically for Galaxy-branded smartphones.
In addition, the firmware update also brings device stability improvements, bug fixes and other improvements for performance.
Software Update A320FLXXU2CRE3 for Galaxy A3 (2017) is rolling out as OTA update. The updates will gradually release to everyone. You can also check manually for updates, go to Settings > About device > System update.