SiYuan before v3.7.4 contains an information disclosure vulnerability in the /api/filetree/authFilePublishAccess endpoint, which is registered with CheckAuth only and is reachable anonymously. The endpoint never sets a failure code, so its outcome is signalled entirely by the response message and by the presence of a Set-Cookie header, and these signals differ across access tiers. By submitting requests with an empty password for a candidate document identifier, an anonymous attacker can distinguish whether a document is public/nonexistent, password-protected, or exists at the hidden or forbidden tier, thereby confirming the existence of documents they are not permitted to access. Because hidden and forbidden entries store an empty password, such requests also cause the server to issue a publish-auth cookie for forbidden documents.

Affected: Go: github.com/siyuan-note/siyuan/kernel

### Summary

`/api/filetree/authFilePublishAccess` is registered with `CheckAuth` only and is reachable anonymously. It never sets a failure code, so its outcome is signalled entirely by the response message and by whether a `Set-Cookie` header is present. Those two signals differ across access tiers, which lets an anonymous caller determine, for any candidate document identifier, whether that document is public or nonexistent, password-protected, or exists at the hidden or forbidden tier.

Separately, hidden and forbidden entries carry an empty password. Submitting `password:""` therefore satisfies the equality check for them, and the server responds by issuing `Set-Cookie: publish-auth-<docID>` for a document whose own tier is forbidden.

### Details

**Route,** identical on both refs:

```go ginServer.Handle("POST", "/api/filetree/authFilePublishAccess", model.CheckAuth, authFilePublishAccess) ```

No `CheckAdminRole`, no `CheckReadonly`.

**Handler,** `kernel/api/filetree.go:1608` on the development branch and `:1421` on master. `ret.Code` is never assigned on the failure path, so every response carries `code:0`. The branch is:

```go if item.Password == password { // SetPublishAuthCookie } else { ret.Msg = Conf.Language(285) } ```

**The cookie is issued for forbidden documents.** Entries at the hidden and forbidden tiers store `Password == ""`. A request with `password:""` therefore makes `item.Password == password` true for them, and the handler takes the succ…