Reachable assertion in Elasticsearch - CVE-2026-63140
Published: July 22, 2026
Vulnerability identifier: #VU139146
CSH Severity: Low
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63140
CWE-ID: CWE-617
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to reachable assertion in query parsing when processing a specially crafted search request containing a null value in a specific query clause. A remote user can send a specially crafted search request to cause a denial of service.
Exploitation requires read access to at least one index. In single-node deployments this stops the service, while in multi-node clusters each successful exploit reduces cluster capacity for the affected node.
Affected software
Elasticsearch
How to mitigate CVE-2026-63140
Install security update from vendor's website.
Elasticsearch - addressed in versions 8.19.19, 9.3.8, 9.4.4