OpenSearch Security plugin: DLS not applied on documents linked by has_child or has_parent relation

Description

A flaw was identified in the OpenSearch Security plugin's document-level security (DLS) implementation. DLS restrictions were not correctly applied to search queries that use has_parent or has_child join relations. This could allow an authenticated user to access document contents that should have been restricted by DLS rules.

Impact

An authenticated user with access to an index containing parent/child join relations could bypass DLS restrictions on documents linked by those relations, potentially accessing restricted document contents. This only affects clusters that use both DLS and the join field type on the same index.

Patches

This issue is fixed in OpenSearch 2.19.4 and 3.2.0.

Workarounds

Avoid using the join field type on indices that are subject to DLS rules.