Vulnerability in Elasticsearch

[ Description ]Official 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.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• CERT-FR7 Oct 2026CERTFR-2026-AVI-1276

  Multiple vulnerabilities in Elastic products Translated from French

  Multiple vulnerabilities have been discovered in Elastic products. Some of them allow an attacker to cause privilege escalation, a breach of data confidentiality and a security policy bypass.

  CVE-2026-102406CVE-2026-103006CVE-2026-102404+11 more CVEs
• BSI CERT-Bund6 Oct 2026WID-SEC-2026-3784

  Elasticsearch: Multiple vulnerabilities Translated from German

  CVE-2026-102404CVE-2026-103005CVE-2026-103006+7 more CVEs

[ References ]References

• discuss.elastic.co/t/elasticsearch-8-19-23-9-4-8-9-5-5-security-update-esa-2026-199/390874Vendor Advisory