Cross-site scripting in Firefox ESR and Mozilla Firefox - CVE-2020-15676

Vulnerability identifier: #VU46964

CSH Severity: Medium

CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N]

CVE-ID: CVE-2020-15676

CWE-ID: CWE-79

Exploitation vector: Remote access

Exploit availability: No public exploit available

The disclosed vulnerability allows a remote attacker to perform cross-site scripting (XSS) attacks.

The vulnerability exists due to Firefox sometimes ran the onload handler for SVG elements that the DOM sanitizer decided to remove, resulting in JavaScript being executed after pasting attacker-controlled data into a contenteditable element.

Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform phishing and drive-by-download attacks.

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

Install updates from vendor's website.

Firefox ESR - update to 78.3.0
Mozilla Firefox - update to 81.0
Mozilla Thunderbird - update to 78.3.0
thunderbird (Red Hat package) - addressed in versions 78.3.1-1.el6_10, 78.3.1-1.el7_9, 78.3.1-1.el8_0, 78.3.1-1.el8_1, 78.3.1-1.el8_2
firefox-esr (Alpine package) - update to 78.3.0-r0
firefox (Red Hat package) - addressed in versions 78.3.0-1.el6_10, 78.3.0-1.el7_9, 78.3.0-1.el8_0, 78.3.0-1.el8_1, 78.3.0-1.el8_2
firefox-esr (Debian package) - update to 78.3.0esr-1~deb10u1
thunderbird (Debian package) - update to 1:78.3.1-2~deb10u2
firefox (Ubuntu package) - addressed in versions 81.0+build2-0ubuntu0.16.04.1, 81.0+build2-0ubuntu0.18.04.1, 81.0+build2-0ubuntu0.20.04.1

• https://www.mozilla.org/en-US/security/advisories/mfsa2020-42/
• https://www.mozilla.org/en-US/security/advisories/mfsa2020-43/

• Multiple vulnerabilities in Mozilla Firefox and Firefox ESR
• Slackware Linux update for seamonkey
• Cross-site scripting in firefox-esr (Alpine package)
• Cross-site scripting in firefox (Alpine package)
• Arch Linux update for firefox
• Multiple vulnerabilities in Thunderbird
• Red Hat Enterprise Linux 8 update for firefox
• OpenSUSE Linux update for MozillaFirefox
• OpenSUSE Linux update for MozillaFirefox
• Red Hat Enterprise Linux 6 update for firefox
• Red Hat Enterprise Linux 8 update for firefox
• Red Hat Enterprise Linux 8 update for firefox
• Debian update for firefox-esr
• Red Hat Enterprise Linux 7 update for firefox
• Red Hat Enterprise Linux 7 update for thunderbird
• Red Hat Enterprise Linux 6 update for thunderbird
• Red Hat Enterprise Linux 8 update for thunderbird
• Red Hat Enterprise Linux 8 update for thunderbird
• Red Hat Enterprise Linux 8 update for thunderbird
• Debian update for thunderbird
• Gentoo update for Mozilla Firefox, Mozilla Thunderbird
• OpenSUSE Linux update for MozillaThunderbird and mozilla-nspr
• OpenSUSE Linux update for MozillaThunderbird and mozilla-nspr
• Ubuntu update for firefox