Information disclosure in Firefox ESR and Mozilla Firefox - CVE-2021-23953

Vulnerability identifier: #VU50021

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-2021-23953

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 cross-origin information leak when processing PDF files. A remote attacker can create a specially crafted PDF file, trick the victim into opening it and gain access to sensitive information via redirected PDF requests, when said information is served as chunked data.

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

Install updates from vendor's website.

Firefox ESR - update to 78.7.0
Mozilla Firefox - update to 85.0
Mozilla Thunderbird - update to 78.7.0
firefox-esr (Alpine package) - update to 78.7.0-r0
thunderbird (Debian package) - update to 78.7.0-1~deb10u1
firefox-esr (Debian package) - update to 78.7.0esr-1~deb10u1
firefox (Red Hat package) - addressed in versions 78.7.0-2.el7_9, 78.7.0-2.el8_1, 78.7.0-2.el8_2, 78.7.0-2.el8_3
thunderbird (Red Hat package) - addressed in versions 78.7.0-1.el7_9, 78.7.0-1.el8_1, 78.7.0-1.el8_2, 78.7.0-1.el8_3
thunderbird (Alpine package) - update to 78.7.0-r0
thunderbird (Ubuntu package) - update to 1:78.7.1+build1-0ubuntu0.20.10.4
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

• https://www.mozilla.org/en-US/security/advisories/mfsa2021-03/
• https://www.mozilla.org/en-US/security/advisories/mfsa2021-04/

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