Information disclosure in Mozilla Firefox and Firefox ESR - CVE-2021-23961

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Main Vulnerability Database Vulnerabilities #VU50030

Information disclosure in Mozilla Firefox and Firefox ESR - CVE-2021-23961

Published: January 26, 2021 / Updated: April 19, 2021


Vulnerability identifier: #VU50030
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2021-23961
CWE-ID: CWE-200
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to the way Firefox handles requests to internal resources. A remote attacker can create a specially crafted web page and combined with slipstream research techniques collect information about hosts in internal network as well as services running on the user's local machine.


Affected software

Mozilla Firefox
Firefox ESR
Arch Linux
Gentoo Linux
SUSE Manager Server
SUSE Manager Retail Branch Server
SUSE Manager Proxy
SUSE CaaS Platform
SUSE Enterprise Storage
Red Hat Enterprise Linux Server
Red Hat Enterprise Linux Desktop
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux Workstation
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power, big endian
SUSE OpenStack Cloud Crowbar
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for x86_64
SUSE OpenStack Cloud
HPE Helion Openstack
Anolis OS
Red Hat Enterprise Linux for x86_64 - Extended Update Support
Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat Enterprise Linux for ARM 64 - Extended Update Support
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
Red Hat Enterprise Linux Server - TUS
SUSE Linux Enterprise Debuginfo
SUSE Linux Enterprise Server
SUSE Linux Enterprise Server for SAP
SUSE Linux Enterprise Software Development Kit
SUSE Linux Enterprise High Performance Computing
SUSE Linux Enterprise Module for Desktop Applications
SUSE Linux Enterprise Workstation Extension
Ubuntu
Red Hat Enterprise Linux Server for x86_64 - Update Services for SAP Solutions
Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions
firefox-esr (Debian package)
firefox (Red Hat package)
thunderbird (Red Hat package)
firefox
thunderbird
MozillaFirefox-translations-other
MozillaFirefox-translations-common
MozillaFirefox-devel
MozillaFirefox-debugsource
MozillaFirefox-debuginfo
MozillaFirefox
MozillaThunderbird-translations-other
MozillaThunderbird-translations-common
MozillaThunderbird-debugsource
MozillaThunderbird-debuginfo
MozillaThunderbird
firefox (Ubuntu package)
Mozilla Thunderbird

How to mitigate CVE-2021-23961

Install updates from vendor's website.

Mozilla Firefox - update to 85.0
Firefox ESR - update to 78.10.0
Mozilla Thunderbird - update to 78.10.0
firefox-esr (Debian package) - update to 78.10.0esr-1~deb10u1
firefox (Red Hat package) - addressed in versions 78.10.0-1.el7_9, 78.10.0-1.el8_1, 78.10.0-1.el8_2, 78.10.0-1.el8_3
thunderbird (Red Hat package) - addressed in versions 78.10.0-1.el7_9, 78.10.0-1.el8_1, 78.10.0-1.el8_2, 78.10.0-1.el8_3
firefox - update to 78.10.0-1.0.1
thunderbird - update to 78.10.0-1.0.1
MozillaFirefox-translations-other - addressed in versions 78.10.0-3.139.1, 78.10.0-8.38.1, 78.10.0-78.126.1
MozillaFirefox-translations-common - addressed in versions 78.10.0-3.139.1, 78.10.0-8.38.1, 78.10.0-78.126.1, 78.10.0-112.57.2
MozillaFirefox-devel - addressed in versions 78.10.0-3.139.1, 78.10.0-8.38.1, 78.10.0-112.57.2
MozillaFirefox-debugsource - addressed in versions 78.10.0-3.139.1, 78.10.0-8.38.1, 78.10.0-112.57.2
MozillaFirefox-debuginfo - addressed in versions 78.10.0-3.139.1, 78.10.0-8.38.1, 78.10.0-78.126.1, 78.10.0-112.57.2
MozillaFirefox - addressed in versions 78.10.0-3.139.1, 78.10.0-8.38.1, 78.10.0-78.126.1, 78.10.0-112.57.2
MozillaThunderbird-translations-other - update to 78.10.0-8.23.1
MozillaThunderbird-translations-common - update to 78.10.0-8.23.1
MozillaThunderbird-debugsource - update to 78.10.0-8.23.1
MozillaThunderbird-debuginfo - update to 78.10.0-8.23.1
MozillaThunderbird - update to 78.10.0-8.23.1
firefox (Ubuntu package) - addressed in versions 85.0+build1-0ubuntu0.16.04.1, 85.0+build1-0ubuntu0.18.04.1, 85.0+build1-0ubuntu0.20.04.1, 85.0+build1-0ubuntu0.20.10.1

External References

Related Security Bulletins