Detections
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Mozilla Firefox < 155.0

critical Nessus Plugin ID 342204

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Synopsis

A web browser installed on the remote Windows host is affected by multiple vulnerabilities.

Description

The version of Firefox installed on the remote Windows host is prior to 155.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-82 advisory.

 - Privilege escalation due to invalid pointer in the Graphics component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84131)

 - Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84121)

 - Use-after-free in the JavaScript: GC component. This vulnerability was fixed in Firefox 155 and Firefox ESR 153.2. (CVE-2026-84118)

 - Sandbox escape due to use-after-free in the DOM: Navigation component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84119)

 - 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)

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 version 155.0 or later.

See Also

https://www.mozilla.org/en-US/security/advisories/mfsa2026-82/

Plugin Details

Severity: Critical

ID: 342204

File Name: mozilla_firefox_155_0.nasl

Version: 1.5

Type: Local

Agent: windows

Family: Windows

Published: 9/1/2026

Updated: 9/11/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5

Percentile: 93.42

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.8

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

CVSS Score Source: CVE-2026-84143

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.8

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

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

Vulnerability Information

CPE: cpe:/a:mozilla:firefox

Required KB Items: installed_sw/Mozilla Firefox

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 9/1/2026

Vulnerability Publication Date: 9/1/2026

Reference Information

CVE: CVE-2026-84118, CVE-2026-84119, CVE-2026-84120, CVE-2026-84121, CVE-2026-84122, CVE-2026-84123, CVE-2026-84124, CVE-2026-84125, CVE-2026-84126, CVE-2026-84128, CVE-2026-84129, CVE-2026-84130, CVE-2026-84131, CVE-2026-84132, CVE-2026-84133, CVE-2026-84134, CVE-2026-84136, CVE-2026-84137, CVE-2026-84138, CVE-2026-84139, CVE-2026-84140, CVE-2026-84141, CVE-2026-84142, CVE-2026-84143, CVE-2026-84144, CVE-2026-84145

IAVA: 2026-A-0924