Mozilla Firefox ESR < 91.1

high Nessus Plugin ID 153106


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


The version of Firefox ESR installed on the remote macOS or Mac OS X host is prior to 91.1. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2021-41 advisory.

- When delegating navigations to the operating system, Thunderbird would accept the `mk` scheme which might allow attackers to launch pages and execute scripts in Internet Explorer in unprivileged mode. This bug only affects Thunderbird for Windows. Other operating systems are unaffected. (CVE-2021-38492)

- Mozilla developers Tyson Smith, Christian Holler, and Gabriele Svelto reported memory safety bugs present in Thunderbird 78.13.0. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. (CVE-2021-38495)

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


Upgrade to Mozilla Firefox ESR version 91.1 or later.

See Also

Plugin Details

Severity: High

ID: 153106

File Name: macos_firefox_91_1_esr.nasl

Version: 1.5

Type: local

Agent: macosx

Published: 9/8/2021

Updated: 12/1/2023

Supported Sensors: Nessus Agent, Nessus

Risk Information


Risk Factor: Medium

Score: 5.9


Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5.3

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

CVSS Score Source: CVE-2021-38495


Risk Factor: High

Base Score: 8.8

Temporal Score: 7.9

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/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_esr

Required KB Items: MacOSX/Firefox/Version

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 9/7/2021

Vulnerability Publication Date: 9/7/2021

Reference Information

CVE: CVE-2021-38492, CVE-2021-38495

IAVA: 2021-A-0405