Detections
Analytics

Elasticsearch 8.19.x < 8.19.20 / 9.3.x / 9.4.x < 9.4.5 / 9.5.x < 9.5.1 DoS (ESA-2026-120)

medium Nessus Plugin ID 338343

Language:

Synopsis

The remote host is missing a security update.

Description

The version of Elasticsearch installed on the remote host is 8.19.x prior to 8.19.20, or 9.3.x or 9.4.x prior to 9.4.5, or 9.5.x prior to 9.5.1. It is, therefore, affected by a vulnerability as referenced in the ESA-2026-120 advisory.

 - Elasticsearch does not enforce an upper bound on a user-supplied count accepted by a search highlighting option, and the allocation derived from that count is not accounted against any circuit breaker. An authenticated user holding only read privileges on a single searchable index can submit one small search request that causes the node to reserve an excessively large internal data structure. The allocation occurs before the existing highlighting safety limits are evaluated, so memory exhaustion raises a fatal error that terminates the Elasticsearch node process. (CVE-2026-72639)

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 8.19.20, 9.4.5, or 9.5.1 or later as appropriate for your release branch.

See Also

http://www.nessus.org/u?0cea669e

Plugin Details

Severity: Medium

ID: 338343

File Name: elasticsearch_ESA-2026-120.nasl

Version: 1.2

Type: Combined

Agent: unix

Family: Misc.

Published: 8/20/2026

Updated: 8/21/2026

Configuration: Enable thorough checks (optional)

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5

Percentile: 93.82

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5

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

CVSS Score Source: CVE-2026-72639

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.7

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

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: 8/13/2026

Vulnerability Publication Date: 8/13/2026

Reference Information

CVE: CVE-2026-72639

CWE: 789