I can't find patch file for magento open source 2.1.7 version addressing authorize.net md5 hash issue. Is there any patch for 2.1.x? I don't want to upgrade magento version right now.
I installed the composer based patch
Auth.net.md5.composer-2019-02-27-11-51-12.patch for Magento version 2.1.15 and it got applied successfully without any issues. The payment is also working fine. Try applying Magento 2.2.x Authorize.net MD5 patch in your local Magento 2.1.x or dev environment, test it and move live.
patch -p0 < Auth.net.md5.composer-2019-02-27-11-51-12.patch