Hello,
As temp patch, you can edit the file "components/com_hikamarket/controllers/product.php" and replace
$cancel_url = urldecode(hikaInput::get()->getString('cancel_url', ''));
if(!empty($cancel_url) && !hikamarket::disallowUrlRedirect($cancel_url))
$app->redirect( base64_decode($cancel_url) );
By
$cancel_url = urldecode(hikaInput::get()->getString('cancel_url', ''));
if(!empty($cancel_url) && strpos($cancel_url,'http')!==0 && strpos($cancel_url,'/')!==0)
$cancel_url = base64_decode($cancel_url);
if(!empty($cancel_url) && !hikamarket::disallowUrlRedirect($cancel_url))
$app->redirect( $cancel_url );
It will unsure that the the string is in base64 to decode it.
Regards,