Detections
Analytics

Mozilla Firefox ESR < 140.9

critical Nessus Plugin ID 303472

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Synopsis

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

Description

The version of Firefox ESR installed on the remote Windows host is prior to 140.9. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-22 advisory.

 - Privilege escalation in the Netmonitor component. This vulnerability affects Firefox < 149, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9. (CVE-2026-4717)

 - Sandbox escape in the Responsive Design Mode component. This vulnerability affects Firefox < 149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9. (CVE-2026-4692)

 - Race condition, use-after-free in the Graphics: WebRender component. This vulnerability affects Firefox < 149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
 (CVE-2026-4684)

 - Incorrect boundary conditions in the Graphics: Canvas2D component. This vulnerability affects Firefox < 149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
 (CVE-2026-4685, CVE-2026-4686, CVE-2026-4706, CVE-2026-4707)

 - Sandbox escape due to incorrect boundary conditions in the Telemetry component. This vulnerability affects Firefox < 149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
 (CVE-2026-4687)

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 140.9 or later.

See Also

https://www.mozilla.org/en-US/security/advisories/mfsa2026-22/

Plugin Details

Severity: Critical

ID: 303472

File Name: mozilla_firefox_140_9_esr.nasl

Version: 1.5

Type: Local

Agent: windows

Family: Windows

Published: 3/24/2026

Updated: 3/27/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.4

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-2026-4717

CVSS v3

Risk Factor: Critical

Base Score: 10

Temporal Score: 9

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:P/RL:O/RC:C

CVSS Score Source: CVE-2026-4692

Vulnerability Information

CPE: cpe:/a:mozilla:firefox_esr

Required KB Items: installed_sw/Mozilla Firefox ESR

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 3/24/2026

Vulnerability Publication Date: 6/10/2025

Reference Information

CVE: CVE-2025-59375, CVE-2026-4684, CVE-2026-4685, CVE-2026-4686, CVE-2026-4687, CVE-2026-4688, CVE-2026-4689, CVE-2026-4690, CVE-2026-4691, CVE-2026-4692, CVE-2026-4693, CVE-2026-4694, CVE-2026-4695, CVE-2026-4696, CVE-2026-4697, CVE-2026-4698, CVE-2026-4699, CVE-2026-4700, CVE-2026-4701, CVE-2026-4702, CVE-2026-4704, CVE-2026-4705, CVE-2026-4706, CVE-2026-4707, CVE-2026-4708, CVE-2026-4709, CVE-2026-4710, CVE-2026-4711, CVE-2026-4712, CVE-2026-4713, CVE-2026-4714, CVE-2026-4715, CVE-2026-4716, CVE-2026-4717, CVE-2026-4718, CVE-2026-4719, CVE-2026-4720, CVE-2026-4721

IAVA: 2026-A-0274