CVE-2026-63140: Elastic Elasticsearch

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

Reachable Assertion (CWE-617) in Elasticsearch can lead to denial of service via Input Data Manipulation (CAPEC-153). A specially crafted search request containing a null value in a specific query clause causes an internal assertion to be raised during query parsing. Because Elasticsearch treats assertion failures as fatal errors, this terminates the affected node process. A low-privileged authenticated user with read access to at least one index can exploit this condition with a single request to cause a node to terminate, disrupting search availability. In a single-node deployment this fully stops Elasticsearch; in a multi-node cluster it reduces cluster capacity for each affected node.

Affected products

• Elastic Elasticsearch: from 8.0.0, before 8.19.19 (fixed in 8.19.19); from 9.0.0, before 9.3.8 (fixed in 9.3.8); from 9.4.0, before 9.4.4 (fixed in 9.4.4)

Published 2026-07-21. Last modified 2026-08-07.