Detections
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Mozilla Firefox ESR < 140.15

critical Nessus Plugin ID 342132

Synopsis

A web browser installed on the remote macOS or Mac OS X host is affected by multiple vulnerabilities.

Description

The version of Firefox ESR installed on the remote macOS or Mac OS X host is prior to 140.15. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-84 advisory.

 - Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154 and Thunderbird 154. (CVE-2026-75874)

 - Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 153, Thunderbird 153, and Firefox ESR 140.15. (CVE-2026-16365)

 - Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84120)

 - Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84122)

 - Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, Thunderbird 140.13, and Firefox ESR 140.15. (CVE-2026-16371)

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

Solution

Upgrade to Mozilla Firefox ESR version 140.15 or later.

See Also

https://www.mozilla.org/en-US/security/advisories/mfsa2026-84/

Plugin Details

Severity: Critical

ID: 342132

File Name: macos_firefox_140_15_esr.nasl

Version: 1.1

Type: Local

Agent: macosx

Published: 9/1/2026

Updated: 9/1/2026

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5

Percentile: 93.74

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.4

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

CVSS Score Source: CVE-2026-75874

CVSS v3

Risk Factor: Critical

Base Score: 10

Temporal Score: 8.7

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

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

Vulnerability Information

CPE: cpe:/a:mozilla:firefox_esr

Required KB Items: installed_sw/Mozilla Firefox ESR

Exploit Ease: No known exploits are available

Patch Publication Date: 9/1/2026

Vulnerability Publication Date: 7/21/2026

Reference Information

CVE: CVE-2026-16365, CVE-2026-16371, CVE-2026-75874, CVE-2026-84119, CVE-2026-84120, CVE-2026-84121, CVE-2026-84122, CVE-2026-84124, CVE-2026-84131, CVE-2026-84143, CVE-2026-84145

IAVA: 2026-A-0755-S, 2026-A-0876