CVE-2026-72647 in Elasticsearch
Summary
by MITRE • 08/13/2026
Uncontrolled Recursion (CWE-674) in Elasticsearch can lead to denial of service via Serialized Data with Nested Payloads (CAPEC-230). An authenticated user holding only read privileges on a single index can submit one specially crafted search request whose deeply nested structure is processed without a depth limit, exhausting the thread stack and terminating the affected node.
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Analysis
by VulDB Data Team • 08/13/2026
Uncontrolled recursion represents a fundamental flaw in software design that occurs when a function or process calls itself repeatedly without proper termination conditions, leading to resource exhaustion and system instability. This vulnerability class is categorized under CWE-674 and manifests particularly dangerous behaviors in distributed systems like Elasticsearch where data processing operations can be manipulated by malicious actors. The specific implementation of this weakness in Elasticsearch demonstrates how seemingly benign search operations can become weaponized when the system fails to enforce recursion depth limits during serialized data processing.
The technical exploitation of this vulnerability occurs through crafted search requests that contain deeply nested payload structures within serialized data formats such as JSON or binary protocols used by Elasticsearch. When an authenticated user with read-only privileges on a specific index submits such a request, the Elasticsearch engine processes the nested structure without enforcing any recursion depth restrictions. This allows the system to recursively traverse the nested elements until it exhausts the available thread stack space, ultimately causing the affected node to crash or become unresponsive. The vulnerability leverages CAPEC-230's pattern of serialized data manipulation where attackers can construct payloads that appear legitimate but contain malicious nesting structures designed to overwhelm system resources.
The operational impact of this vulnerability extends beyond simple denial of service attacks as it represents a critical security weakness that can be exploited by insiders or compromised accounts with minimal privileges. An attacker with read-only access can effectively bring down entire Elasticsearch clusters by targeting individual nodes through carefully constructed search queries, making this particularly dangerous in production environments where cluster stability is paramount. The vulnerability's exploitation does not require elevated privileges or complex attack chains, which makes it an attractive target for adversaries seeking to disrupt services without triggering sophisticated security monitoring systems.
Mitigation strategies for this vulnerability must address both the immediate technical flaw and implement broader defensive measures within Elasticsearch deployments. Organizations should configure recursion limits in their Elasticsearch instances through proper parameter settings that prevent deep nesting during search operations. The implementation of resource quotas and request timeouts can help contain the impact even when recursion limits are exceeded. Security teams should also implement monitoring for unusual search patterns that might indicate attempted exploitation, including tracking query complexity metrics and implementing automated alerts for potentially dangerous nested structures. Additionally, regular security assessments and penetration testing should verify that recursion protections are properly configured and functioning as intended.
From a compliance and framework perspective, this vulnerability directly relates to several security standards and methodologies including the ATT&CK framework's privilege escalation and denial of service tactics. The weakness demonstrates how basic programming errors can lead to serious security implications when combined with proper attack vectors and access levels. Organizations should ensure their Elasticsearch deployments follow security best practices outlined in frameworks such as NIST SP 800-53, which emphasizes the importance of input validation and resource management controls. The vulnerability also highlights the need for proper application security testing including static analysis tools that can detect potential recursion issues in code implementations, ensuring that defensive programming practices are maintained throughout the development lifecycle.