The Yuko Yuko (aka jp.co.yukoyuko.android.yukoyuko_android) application 1.0.5 and earlier for Android does not verify X.509 certificates from SSL servers, which allows man-in-the-middle attackers to spoof servers and obtain sensitive information via a crafted certificate.
https://play.google.com/store/apps/details?id=jp.co.yukoyuko.android.yukoyuko_android