Elasticsearch DoS via Assertion Failure in Query Parsing
CVE-2026-63140 Published on July 21, 2026
Reachable Assertion in Elasticsearch Leading to Denial of Service
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.
Vulnerability Analysis
CVE-2026-63140 is exploitable with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Weakness Type
What is an assertion failure Vulnerability?
The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.
CVE-2026-63140 has been classified to as an assertion failure vulnerability or weakness.
Products Associated with CVE-2026-63140
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Affected Versions
Elasticsearch:- Version 9.0.0, <= 9.3.7 is affected.
- Version 9.4.0, <= 9.4.3 is affected.
- Version 8.0.0, <= 8.19.18 is affected.