snprintf will put the terminator in. We don't have to.

src/zm_user.cpp

@@ -297,7 +297,6 @@ User *zmLoadAuthUser( const char *auth, bool use_remote_addr ) {
       for ( unsigned int j = 0; j < md5len; j++ ) {
         snprintf(&auth_md5[2*j], 2, "%02x", md5sum[j]);
       }
-      auth_md5[md5len*2+1] = '\0';
       Debug( 1, "Checking auth_key '%s' -> auth_md5 '%s' == '%s'", auth_key, auth_md5, auth );
 
       if ( !strcmp( auth, auth_md5 ) ) {