Elasticsearch versions before 6.8.13 and 7.9.2 contain a document disclosure flaw when Document or Field Level Security is used

Elasticsearch versions before 6.8.13 and 7.9.2 contain a document disclosure flaw when Document or Field Level Security is used. Search queries do not properly preserve security permissions when executing certain complex queries. This could result in the search disclosing the existence of documents the attacker should not be able to view. This could result in an attacker gaining additional insight into potentially sensitive indices.