CVE-2026-102408
MediumCVSS 4.3Exploitation Probability (EPSS)
Low risk25th percentile - higher than 25% of all known CVEs
Summary
Inefficient regular expression complexity in Elasticsearch's ES|QL CHUNK function can lead to denial of service via catastrophic backtracking. A user with read access to a text-based index can submit a crafted regex causing excessive CPU consumption and degrading query throughput for other tenants.
Risk Assessment
The risk involves performance degradation of the Elasticsearch cluster, potentially affecting service availability for other users, though the cluster does not crash.
Recommendation
Upgrade Elasticsearch to a patched version and restrict read access to text-based indices for untrusted users. Monitor CPU usage in the context of ES|QL queries.
Other vulnerabilities in Elasticsearch
See all- CVE-2015-4165High
The snapshot API in Elasticsearch before version 1.6.0 is vulnerable when another application exists on the system that can read Lucene files and execute code from them. This allows remote authenticated users to write to and create arbitrary snapshot metadata files, potentially executing arbitrary code.
- CVE-2026-103009High
Elasticsearch contains an authorization bypass vulnerability in the Remote Cluster Security (RCS) 2.0 model. An attacker with a valid API key can send a specially crafted cross-cluster search request that is authorized for one index but actually operates on a different, unauthorized index, exposing its data.
- CVE-2026-103008Medium
Uncontrolled Recursion (CWE-674) in Elasticsearch can lead to Denial of Service via a specially crafted request that causes the server to construct and process a deeply nested data structure with no bound on recursion depth. Elasticsearch contains this weakness in how it builds and serializes geometry values produced by scripted runtime fields. An authenticated user with read access to a single index can submit a request defining such a field with a script that produces a deeply nested structure, causing the affected node to terminate. The node does not recover automatically on all deployments and may require manual intervention.
- CVE-2026-103007High
Elasticsearch contains an incorrect authorization vulnerability in a configurable, non-default privilege that allows an administrator to delegate limited role-management capability. Due to incomplete enforcement of scope, a user with this privilege can expand their access to indices that should remain restricted, including internal security data.
- CVE-2026-103006Medium
Uncontrolled Recursion (CWE-674) in Elasticsearch can lead to Denial of Service via a specially crafted, deeply nested request submitted to the aggregation feature of the search API. Elasticsearch contains this weakness in its search aggregation processing. An authenticated user with read access to a single index can submit a crafted request containing deeply nested aggregation definitions, triggering unbounded recursive execution that exhausts the server process's resources and causes the affected node to terminate. The node does not recover automatically and requires manual intervention.
- CVE-2026-103005Medium
Memory Allocation with Excessive Size Value (CWE-789) in Elasticsearch can lead to denial of service via Excessive Allocation (CAPEC-130). An authenticated user with connector management privileges could cause the cluster to allocate an uncontrolled amount of memory when connector resources with an excessively large `description` field are created and subsequently accessed, exhausting available heap memory and crashing the affected node.
- CVE-2026-102411Medium
Elasticsearch does not limit total memory used when retrieving multiple index templates, despite per-resource limits. A user with manage_index_templates privilege can register many templates, and retrieving them together exhausts heap memory, causing node failure and denial of service.
- CVE-2026-102409Medium
Uncontrolled recursion in Elasticsearch allows an authenticated low-privileged user to terminate an Elasticsearch node, resulting in denial of service. The vulnerability is related to excessive resource allocation.
- CVE-2026-102407Medium
Incorrect authorization in Elasticsearch allows an authenticated user with privileges over a single resource to modify a data stream they are not authorized for. This can allow data injection or affect searchability, but does not enable reading the stream's contents.
- CVE-2026-102404Medium
Uncontrolled resource consumption in Elasticsearch allows a low-privileged user to crash a node with a crafted query causing uncontrolled memory growth. The condition can be triggered repeatedly, including via queries in shared resources, causing persistent cluster unavailability.
Original NVD description (English source)
Inefficient Regular Expression Complexity (CWE-1333) in Elasticsearch can lead to denial of service via Regular Expression Exponential Blowup (CAPEC-492). The ES|QL CHUNK function's recursive chunking strategy accepts a list of user-supplied regular expressions used as text-splitting separators, without validating their computational complexity or bounding their execution time. An authenticated user with read access to any text-based index can submit a specially crafted regular expression that triggers catastrophic backtracking, consuming excessive CPU on Elasticsearch worker threads and degrading query throughput for other tenants on the affected node. The cluster does not crash as a result of this issue.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

