Vulnerability · Published Jul 21, 2026 · Assigned by elastic
CVE-2026-63140Reachable Assertion in Elasticsearch Leading to Denial of Service
Medium 6.5
In plain English
A medium-severity security flaw in Elasticsearch from Elastic. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities).
Official description
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 (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Elastic | Elasticsearch | 9.0.0 – through 9.3.79.4.0 – through 9.4.38.0.0 – through 8.19.18 |
Weakness: CWE-617 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H