What’s Vulnerable › Vulnerabilities
CVE-2026-103009: Authorization Bypass Through User-Controlled Key in Elasticsearch Leading to Information Disclosure
- Severity: high (CVSS 7.1 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.2% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-10-06 · updated 2026-10-09
- Weakness: CWE-639
Description
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
- Elasticsearch: from 8.13.0 before 8.19.23; from 9.0.0 before 9.4.8; from 9.5.0 before 9.5.5 — fixed in 8.19.23, 9.4.8, 9.5.5
How to fix
Upgrade to a fixed version: Elasticsearch 8.19.23, 9.4.8, 9.5.5. Check the vendor advisory for mitigations.
References
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