jp-version-check.php

<?php

function can_use_version( $version ) {
	$secure_jetpacks = array(
		'1.9' => '1.9.3',
		'2.0' => '2.0.5',
		'2.1' => '2.1.3',
		'2.2' => '2.2.6',
		'2.3' => '2.3.6',
		'2.4' => '2.4.3',
		'2.5' => '2.5.1',
		'2.6' => '2.6.2',
		'2.7' => '2.7.1',
		'2.8' => '2.8.1',
		'2.9' => '2.9.3',
	);

	$float_version = (string) floatval( $version );

	if ( isset( $secure_jetpacks[ $float_version ] ) ) {
		if ( version_compare( $version, $secure_jetpacks[ $float_version ], '<' ) ) {
			return false;
		}
	}

	// It passed the check! Return true!  Not outdated or insecure!
	return true;
}