CVE-2026-72683 in Elasticsearch
Summary
by MITRE • 08/13/2026
A flaw in Elasticsearch allows an authenticated user with the privileges required to invoke the simulate pipeline API endpoint (https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-ingest-simulate) to submit a request that causes a self-referential data structure to be created. When a specific internal component later processes that structure, the operation recurses without bound and raises a fatal error that is not handled by the surrounding execution path, terminating the affected node process and resulting in a denial of service.
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Analysis
by VulDB Data Team • 08/13/2026
This vulnerability exists within the elasticsearch distributed search and analytics engine where an authenticated user with specific privileges can exploit a flaw in the simulate pipeline API endpoint. The issue stems from improper handling of self-referential data structures during internal processing, creating an infinite recursion scenario that ultimately leads to process termination and complete denial of service for the affected node. The vulnerability specifically targets users who possess the necessary permissions to invoke ingest pipeline simulation functionality, making it a privilege-based attack vector rather than a generic exploit.
The technical implementation of this flaw involves the creation of a self-referential data structure through the simulate pipeline API endpoint which allows users to test ingest pipelines without actually executing them. When the system processes this maliciously constructed data structure, an internal component begins recursive operations that spiral out of control without proper termination conditions or error handling mechanisms. This recursive processing continues until system resources are exhausted, resulting in a fatal error that crashes the node process. The absence of proper bounds checking and recursion depth limits in the internal processing logic creates this exploitable condition. According to the common weakness enumeration framework, this vulnerability maps to cwe-674 which describes "Uncontrolled Recursion" as a weakness where recursive calls are not properly bounded or terminated.
The operational impact of this vulnerability is significant as it can be leveraged by authenticated attackers to cause complete service disruption within elasticsearch clusters. Since the attack requires only standard user privileges to access the simulate pipeline API, it represents a low-barrier denial of service threat that can be executed without elevated system access. The termination of individual node processes creates cascading effects in distributed systems where cluster availability depends on multiple nodes functioning correctly. Organizations relying on elasticsearch for critical data operations face potential business disruption when affected nodes become unavailable due to this vulnerability.
Mitigation strategies should focus on both immediate defensive measures and long-term architectural improvements. Organizations must first ensure that the simulate pipeline API endpoint is properly restricted through role-based access controls, limiting access to only those users who absolutely require this functionality. Additionally, implementing proper recursion depth limits and resource monitoring within elasticsearch configurations can help detect and prevent runaway processing scenarios. The recommended approach includes updating to patched versions of elasticsearch where appropriate, as well as implementing network-level restrictions to limit access to vulnerable endpoints. From an att&ck framework perspective, this vulnerability aligns with tactics such as privilege escalation and denial of service, requiring defensive measures that address both access control and resource management aspects of the attack surface.