GHSA-9gjv-jvm7-vv2v

## Summary

Users with the **Guest** role could receive private sub-object data (e.g. private alternate names, private addresses, private note/citation/media handles) through list API endpoints such as `GET /api/people/`, `GET /api/places/`, `GET /api/events/`, and all other object list endpoints.

**This does not expose objects (people, places, events, …) that are themselves marked private.** Top-level private objects are correctly excluded from all responses. Only sub-object data attached to otherwise-public objects is affected.

## Affected Versions

All versions of Gramps Web API prior to the fix.

## Root Cause

The vulnerability originates from the behaviour of `PrivateProxyDb.iter_*()` in **Gramps core**. The `ProxyDbBase.__iter_object()` helper, which backs all `iter_*()` methods in `PrivateProxyDb`, correctly filters out top-level private objects but returns the remaining objects **unsanitized** — i.e. without stripping private sub-object references. In contrast, `PrivateProxyDb.get_*_from_handle()` does call the appropriate `sanitize_*()` function.

Gramps Web API's `ModifiedPrivateProxyDb` (which wraps the raw database for non-admin users) inherited this behaviour without override.

The same issue affects Gramps desktop features that consume `iter_*()` output: reports and exports generated via Gramps desktop using `PrivateProxyDb` may also include private sub-object data that should have been stripped.

## Conditions Required

**This issue only affects trees in which sub-objects have been explicitly marked private in Gramps desktop.** The Gramps Web frontend UI does not expose controls for setting the private flag on sub-objects (alternate names, addresses, notes, citations, media references, event references, etc.). In practice, such flags are set in Gramps desktop and then synced or imported into Gramps Web.

## Impact

When the conditions above are met, a user with the Guest role querying any list endpoint receives:

- **Full content** of private embedded sub-objects on people, such as alternate names (first name, surname, etc.) and addresses (street, city, etc.). - **Handles referencing** private notes, citations, and media attached to places, events, sources, and other objects. These reveal the *existence* of private linked objects but not their content; fetching those objects by handle is correctly blocked by the proxy.

## Fix

`ModifiedPrivateProxyDb` now overrides all `iter_*()` object methods to check `obj.get_privacy()` directly on the already-loaded object (eliminating the redundant per-object refetch) and to call the appropriate `sanitize_*()` function before yielding each object. This is consistent with the behaviour of `get_*_from_handle()` in `PrivateProxyDb`.