VitaFit cloud API before 2026-10-30 contained an authentication bypass vulnerability that allows remote attackers to obtain a full session for a victim's account by submitting a linked Google or Facebook account identifier to the POST /front/login/sns/ endpoint without providing proof of ownership from the identity provider. Attackers can forge a login using an identifier exposed through account enumeration to read and modify the victim's profile and delete the account's authentication record, preventing the legitimate user from logging in.