Authorization Bypass Through User-Controlled Key in Elasticsearch Leading to Information Disclosure

Summary

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.

Timeline

1. Oct 6, 2026, 7:31 PM UTCCVE published
2. Oct 6, 2026, 7:52 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Oct 6, 2026, 7:52 PM UTCRecord last updated

Affected versions

• Elastic Elasticsearch

  From 8.13.0 · through 8.19.22; From 9.0.0 · through 9.4.7; From 9.5.0 · through 9.5.4

• elasticsearchBitnami

  From 8.13.0 · fixed in 8.19.23; From 9.0.0 · fixed in 9.4.8; From 9.5.0 · fixed in 9.5.5

References 1