A vulnerability in the XiaozhangBang Voluntary Like System V8.8 allows remote attackers to manipulate the zhekou parameter in the /topfirst.php Pay module, enabling unauthorized discounts. By sending a crafted HTTP POST request with zhekou set to an abnormally low value, an attacker can purchase votes at a reduced cost. Furthermore, by modifying the zid parameter, attackers can influence purchases made by other users, amplifying the impact. This issue stems from insufficient server-side validation of these parameters, potentially leading to economic loss and unfair manipulation of vote counts.