Elasticsearch 9.0.x < 9.4.9 / 9.5.x < 9.5.6 Incorrect Authorization (ESA-2026-209)

medium Nessus Plugin ID 375646

Synopsis

The remote host is missing a security update.

Description

The version of Elasticsearch installed on the remote host is 9.0.x prior to 9.4.9, or 9.5.x prior to 9.5.6. It is, therefore, affected by a vulnerability as referenced in the ESA-2026-209 advisory.

- Incorrect Authorization (CWE-863) in Elasticsearch can lead to information disclosure via Accessing Functionality Not Properly Constrained by ACLs (CAPEC-1). An authenticated user whose index access is restricted by field-level security can retrieve the value of a constant_keyword field that their role excludes. Some search and query features do not apply the field-level security restriction to this field type. (CVE-2026-115298)

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 9.4.9, or 9.5.6 or later as appropriate for your release branch.

Plugin Details

Severity: Medium

ID: 375646

File Name: elasticsearch_esa_2026_209.nasl

Version: 1.1

Type: Combined

Agent: unix

Family: Misc.

Published: 11/3/2026

Updated: 11/3/2026

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

Temporal Score: 3

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

CVSS Score Source: CVE-2026-115298

CVSS v3

Risk Factor: Medium

Base Score: 4.3

Temporal Score: 3.8

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

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

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

Required KB Items: installed_sw/Elasticsearch

Exploit Ease: No known exploits are available

Patch Publication Date: 11/3/2026

Vulnerability Publication Date: 11/3/2026

Reference Information

CVE: CVE-2026-115298

Detections

Analytics