CVE-2026-106100: Payload: Field-level write access bypass in Payload on MongoDB

### Impact A vulnerability in field-level access control could allow an authenticated user to modify fields they are not permitted to change on documents they can otherwise update. You are affected if: Payload version < `3.87.0` (or a `4.0.0-canary` release before `4.0.0-canary.20`) using the MongoDB adapter (`@payloadcms/db-mongodb`) with any collection that relies on field-level access control to restrict writes under certain conditions. Relational adapters (Postgres, SQLite) are not affected. ### Patches Handling of incoming field data has been hardened so field-level access control is enforced consistently. Users should upgrade to `3.87.0` (or `4.0.0-canary.20` on the `4.x` line) or later. ### Workarounds There is no complete workaround. Upgrading to `3.87.0` (or `4.0.0-canary.20` on the `4.x` line) is recommended.