Information disclosure in Firefox ESR and Mozilla Firefox - CVE-2020-35111

Vulnerability identifier: #VU49022

CSH Severity: Medium

CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2020-35111

CWE-ID: CWE-200

Exploitation vector: Remote access

Exploit availability: No public exploit available

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

The vulnerability exists due to the proxy.onRequest API does not use proxy when viewing source code of the web application. A remote attacker, who controls the web server can obtain user's real IP address, if the user decides to view the web application source code while behind a proxy server.

Firefox ESR
Mozilla Firefox
Arch Linux
Gentoo Linux
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power, big endian
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux Server
Red Hat Enterprise Linux Workstation
Red Hat Enterprise Linux Desktop
CentOS
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for x86_64 - Extended Update Support
Red Hat Enterprise Linux for IBM z Systems - 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 Server - TUS
Ubuntu
Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions
Red Hat Enterprise Linux Server for x86_64 - Update Services for SAP Solutions
firefox-esr (Debian package)
thunderbird (Debian package)
firefox (Red Hat package)
thunderbird (Red Hat package)
firefox-esr (Alpine package)
thunderbird (Alpine package)
firefox (Alpine package)
thunderbird (Ubuntu package)
firefox (Ubuntu package)
Mozilla Thunderbird

Install updates from vendor's website.

Firefox ESR - update to 78.6.0
Mozilla Firefox - update to 84.0
Mozilla Thunderbird - update to 78.6.0
firefox-esr (Debian package) - update to 78.6.0esr-1~deb10u1
thunderbird (Debian package) - update to 78.6.0-1~deb10u1
firefox (Red Hat package) - addressed in versions 78.6.0-1.el7_9, 78.6.0-1.el8_0, 78.6.0-1.el8_1, 78.6.0-1.el8_2, 78.6.0-1.el8_3
thunderbird (Red Hat package) - addressed in versions 78.6.0-1.el7_9, 78.6.0-1.el8_0, 78.6.0-1.el8_1, 78.6.0-1.el8_2, 78.6.0-1.el8_3
firefox-esr (Alpine package) - update to 78.6.0-r0
thunderbird (Alpine package) - update to 78.6.1-r0
firefox (Alpine package) - update to 84.0.1-r0
thunderbird (Ubuntu package) - update to 1:78.6.1+build1-0ubuntu0.20.10.1
firefox (Ubuntu package) - addressed in versions 84.0+build3-0ubuntu0.16.04.1, 84.0+build3-0ubuntu0.18.04.1, 84.0+build3-0ubuntu0.20.04.1, 84.0+build3-0ubuntu0.20.10.1

• https://www.mozilla.org/en-US/security/advisories/mfsa2020-54/
• https://www.mozilla.org/en-US/security/advisories/mfsa2020-55/

• Multiple vulnerabilities in Mozilla Firefox and Firefox ESR
• Multiple vulnerabilities in Mozilla Thunderbird
• Arch Linux update for firefox
• Arch Linux update for thunderbird
• Debian update for firefox-esr
• Debian update for thunderbird
• Red Hat Enterprise Linux 7 update for firefox
• Red Hat Enterprise Linux 8 update for firefox
• Red Hat Enterprise Linux 8.2 update for firefox
• Red Hat Enterprise Linux 8.1 update for firefox
• Red Hat Enterprise Linux 8 update for firefox
• Red Hat Enterprise Linux 7 update for thunderbird
• Red Hat Enterprise Linux 8.2 update for thunderbird
• Red Hat Enterprise Linux 8 update for thunderbird
• CentOS 7 update for thunderbird
• Red Hat Enterprise Linux 8.1 update for thunderbird
• Red Hat Enterprise Linux 8 update for thunderbird
• Information disclosure in firefox-esr (Alpine package)
• Gentoo update for Mozilla Firefox, Mozilla Thunderbird
• Information disclosure in firefox (Alpine package)
• Information disclosure in thunderbird (Alpine package)
• Ubuntu update for thunderbird
• Ubuntu update for firefox