CVE-2026-72686 in Elasticsearch
Summary
by MITRE • 08/13/2026
A flaw in Elasticsearch allows a low-privileged authenticated user to submit a single request containing a crafted user-supplied input. A specific internal component validates the input using a recursive routine and applies no bound to the length of the value being validated, so the validation causes the thread to exhaust its stack. The resulting fatal error is not handled by the surrounding execution paths and terminates the affected node process, producing a denial of service.
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Analysis
by VulDB Data Team • 08/13/2026
This vulnerability represents a critical stack overflow condition within Elasticsearch that enables authenticated users to trigger a denial of service attack through carefully crafted input. The flaw exists in the internal validation mechanism where recursive functions process user-supplied data without implementing length restrictions or stack depth limits. When an attacker submits malicious input, the recursive validation routine consumes excessive stack memory until the thread exhausts its allocated stack space, leading to an unhandled fatal error that terminates the entire Elasticsearch node process.
The technical implementation of this vulnerability stems from improper input validation practices within Elasticsearch's internal components, specifically targeting recursive processing functions that lack adequate boundary checks. According to CWE-674, this represents a recursive function without proper depth control or input length limitations, creating a classic stack overflow scenario. The vulnerability is particularly dangerous because it requires only a single authenticated request to exploit, making it accessible to users with minimal privileges within the system.
From an operational impact perspective, this vulnerability directly affects Elasticsearch node availability and system stability, potentially causing widespread service disruption in environments where multiple nodes are deployed. The termination of individual node processes can lead to cluster instability, data unavailability, and cascading failures that may require manual intervention to restore normal operations. This vulnerability aligns with ATT&CK technique T1499.004 which describes network denial of service attacks targeting services and applications.
The exploitability characteristics indicate that any authenticated user within the Elasticsearch system can leverage this vulnerability to cause system-wide disruption, making it particularly concerning for production environments where access controls may be insufficient or compromised. Organizations should implement immediate mitigations including input validation restrictions, stack depth monitoring, and enhanced error handling mechanisms within their Elasticsearch configurations. The vulnerability demonstrates a fundamental security gap in the software's defensive measures against recursive processing attacks, emphasizing the need for robust boundary checking and proper exception handling in all internal processing routines.
Security teams should prioritize patching affected systems and implementing monitoring for unusual stack consumption patterns or node termination events. Additionally, network segmentation and access control measures should be reviewed to limit potential exploitation vectors, while regular security assessments should focus on validating recursive function implementations across all software components within the Elasticsearch ecosystem.