Auth: fix possible off-by-one
Auth: fix possible off-by-one

No security impact, only triggable by specific API call

robxu9/libssh,pouete/libssh,pouete/libssh,wangshawn/libssh,wangshawn/libssh,kedazo/libssh,jt1/honeypot-libssh,mwgoldsmith/libssh,DouglasHeriot/libssh,Distrotech/libssh,kedazo/libssh,wangshawn/libssh,nviennot/libssh,mwgoldsmith/ssh,pouete/libssh,mwgoldsmith/libssh,Distrotech/libssh,mwgoldsmith/ssh,taikoo/libssh,mwgoldsmith/libssh,elastichosts/libssh,taikoo/libssh,bigcat26/libssh-mod,sebadoom/libssh,robxu9/libssh,DouglasHeriot/libssh,DouglasHeriot/libssh,mwgoldsmith/ssh,mwgoldsmith/libssh,taikoo/libssh,jt1/honeypot-libssh,jt1/honeypot-libssh,DouglasHeriot/libssh,Distrotech/libssh,nviennot/libssh,pouete/libssh,wangshawn/libssh,bigcat26/libssh-mod,elastichosts/libssh,elastichosts/libssh,kedazo/libssh,mwgoldsmith/ssh,sebadoom/libssh,nviennot/libssh,sebadoom/libssh,jt1/honeypot-libssh,robxu9/libssh,nviennot/libssh,robxu9/libssh,Distrotech/libssh,bigcat26/libssh-mod,taikoo/libssh,sebadoom/libssh,bigcat26/libssh-mod,kedazo/libssh