Detections
Analytics

Elasticsearch 8.19.x < 8.19.22 / 9.1.x / 9.3.8 / 9.4.x < 9.4.8 / 9.5.x < 9.5.5 DoS (ESA-2026-189)

medium Nessus Plugin ID 364384

Synopsis

The remote host is missing a security update.

Description

The version of Elasticsearch installed on the remote host is prior to 8.19.22, 9.4.8, or 9.5.5. It is, therefore, affected by a vulnerability as referenced in the ESA-2026-189 advisory.

 - 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.
 (CVE-2026-102408)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Upgrade to Elasticsearch version 9.4.8, or 9.5.5 or later as appropriate for your release branch.

See Also

https://discuss.elastic.co/t/390862

Plugin Details

Severity: Medium

ID: 364384

File Name: elasticsearch_esa_2026_189.nasl

Version: 1.2

Type: Combined

Agent: unix

Family: Misc.

Published: 10/9/2026

Updated: 10/9/2026

Configuration: Enable thorough checks (optional)

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 1.2

Percentile: 0.01

CVSS v2

Risk Factor: Medium

Base Score: 4

Vector: CVSS2#AV:N/AC:L/Au:S/C:N/I:N/A:P

CVSS Score Source: CVE-2026-102408

CVSS v3

Risk Factor: Medium

Base Score: 4.3

Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Vulnerability Information

CPE: cpe:/a:elastic:elasticsearch, cpe:/a:elasticsearch:elasticsearch

Required KB Items: installed_sw/Elasticsearch

Patch Publication Date: 10/6/2026

Vulnerability Publication Date: 10/6/2026

Reference Information

CVE: CVE-2026-102408

IAVA: 2026-A-1094