Elasticsearch 9.5.0 contains a query-correctness defect

A patch release containing the fix is in progress and it is expected to be available within the next week. Our recommendation to defer upgrading to 9.5.0 until 9.5.1 is available remains unchanged.

Further investigation confirmed the impact of this issue was limited to boolean queries containing a must, filter, or should clause, along with a must_not clause on unindexed fields. Such queries can return false-positives returning documents that should have been excluded and report higher document counts than expected.

We have identified the root cause, a fix is in progress, and we are preparing a patch release. We will provide a further update by 10:00 UTC August 6.

Elasticsearch 9.5.0 contains a defect that can cause searches to return incorrect results for any index or data stream that disables indexing on a queried field . A query that excludes values using a must_not clause may fail to exclude them when the targeted field has doc values enabled but is not indexed for search. Affected searches can return documents that should have been excluded and report higher document counts than expected, and results may vary between runs of the same query.

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