CVE-2026-103009: Elastic Elasticsearch

High severity, CVSS 7.1. EPSS: 0.2% chance of exploitation in the next 30 days.

Authorization Bypass Through User-Controlled Key (CWE-639) in Elasticsearch can lead to Information Disclosure via a specially crafted cross-cluster search request that references an unauthorized shard identifier. Elasticsearch contains an authorization bypass weakness in its handling of cross-cluster search requests made through the Remote Cluster Security (RCS) 2.0 model. An authorization check validates a request against one identifying attribute of the target shard, while a separate, independently-supplied identifying attribute in the same request determines which shard is actually accessed. A holder of a cross-cluster API key authorized for one index can craft a request whose two identifying attributes refer to different indices, causing the request to be authorized against an index they can access while actually operating against a different, unauthorized index. This can expose that index's document contents, field mappings, and other metadata, and in limited cases allows modification of retention-lease state on the unauthorized index.

Affected products

• Elastic Elasticsearch: from 8.13.0, before 8.19.23 (fixed in 8.19.23); from 9.0.0, before 9.4.8 (fixed in 9.4.8); from 9.5.0, before 9.5.5 (fixed in 9.5.5)

Published 2026-10-06. Last modified 2026-10-09.