Waline login accepts a non-string email as a match-all MongoDB query

Summary

The login endpoint POST /api/token reads the email field from the request body without checking its type and passes it straight into the MongoDB storage query. When email is not a string (for example a JSON object such as {"$ne": null}), the MongoDB storage adapter's parseWhere silently DROPS the field rather than rejecting the request, producing an empty filter that matches ALL users. The endpoint then verifies the submitted password against the FIRST user returned (user[0]), which in Waline is the first-registered user — the site administrator.

This is a PARTIAL authentication bypass, not a full one. The attacker still needs a valid password for that first user; this is not a zero-knowledge bypass and it does not disclose passwords. Its concrete effects are: (1) the email/identifier factor is removed for the administrator account, (2) user enumeration (a non-string email never fails the "no such user" branch), and (3) credential-stuffing amplification — an attacker can test a leaked or weak password against the administrator account without knowing the administrator's email.

Details

Untyped input — packages/server/src/controller/token.js:17-18:

    const { email, password, code } = this.post();
    const user = await this.modelInstance.select({ email });

email comes from the request body with no type check.

The storage adapter silently drops a non-string key — packages/server/src/service/storage/mongodb.js, parseWhere():

    if (think.isString(where[k])) { filter[parseKey(k)] = { $eq: ... }; continue; }   // intended guard
    if (where[k] === undefined) { ... }
    if (Array.isArray(where[k]) && where[k][0]) { ... operator handling (IN/LIKE/!=/> ...) }

A plain object such as {"$ne": null} is neither a string, undefined, nor an array, so NONE of the branches run and nothing is added to filter for email. The result is filter = {} -> instance.where({}) -> MongoDB find({}) returns every user. (The array form, e.g. ["!=", ""], is a genuine operator injection that reaches $ne with the same match-all effect.)

First user is selected — token.js:22-26:

    if (think.isEmpty(user) || isVerifyUser || isBannedUser) { return this.fail(); }   // match-all -> not empty -> passes
    const checkPassword = this.checkPassword(password, user[0].password);

user[0] is the first record in MongoDB natural (insertion) order, i.e. the earliest-registered user, which in Waline is the administrator.

No upstream type validation — packages/server/src/logic/token.js:37-38:

    async postAction() { await this.useCaptchaCheck(); }