Elasticsearch does not validate a size value from user input before using it to reserve memory for an internal data structure. An authenticated user with only read privileges can submit a crafted request to an API endpoint that triggers an excessively large memory allocation attempt. This causes memory exhaustion, raising a fatal error that terminates the node process and causes denial of service. The vulnerability affects specific versions of Elasticsearch and is not volumetric, meaning a single request suffices to trigger the issue regardless of heap size. Patch availability is confirmed.

An attacker with read-only authentication can cause an Elasticsearch node to crash by triggering excessive memory allocation, resulting in denial of service for that node and degraded cluster health. This disrupts availability but does not imply unauthorized data access or privilege escalation. The attack requires only a single crafted request.

A patch is available for the affected Elasticsearch versions. Users should apply the official fixes to prevent exploitation. Since this is not a cloud service, remediation depends on applying updates to affected deployments. No additional vendor advisory details are provided, so check the vendor's official channels for the latest patch information.