Use-after-free in Firefox ESR and Mozilla Firefox - CVE-2020-6820

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Main Vulnerability Database Vulnerabilities #VU26574

Use-after-free in Firefox ESR and Mozilla Firefox - CVE-2020-6820

Published: April 3, 2020 / Updated: April 7, 2020


Vulnerability identifier: #VU26574
CSH Severity: Critical
CVSS v4: 8.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2020-6820
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability: The vulnerability is being exploited in the wild

Vulnerability details

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a use-after-free error caused by a race condition handling ReadableStream. A remote attacker can create a specially crafted website, trick the victim into visiting it, trigger a use-after-free error and execute arbitrary code on the system.

Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable system.

Note, this vulnerability is being actively exploited in the wild in targeted attacks.


Affected software

Firefox ESR
Mozilla Firefox
Gentoo Linux
Arch Linux
Red Hat Enterprise Linux for Scientific Computing
Red Hat Enterprise Linux for Power, big endian
CentOS
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux Desktop
Red Hat Enterprise Linux Workstation
Red Hat Enterprise Linux Server
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 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
Slackware Linux
Opensuse
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 (Red Hat package)
firefox (Ubuntu package)
firefox-esr (Debian package)
thunderbird (Debian package)
firefox (Alpine package)
thunderbird (Red Hat package)
firefox-esr (Alpine package)
thunderbird (Ubuntu package)
mozjs68 (Alpine package)
thunderbird (Alpine package)
Mozilla Thunderbird

How to mitigate CVE-2020-6820

Install updates from vendor's website.

Firefox ESR - update to 68.6.1
Mozilla Firefox - update to 74.0.1
firefox (Red Hat package) - addressed in versions 68.6.1-1.el6_10, 68.6.1-1.el7_8, 68.6.1-1.el8_0, 68.6.1-1.el8_1
firefox (Ubuntu package) - addressed in versions 74.0.1+build1-0ubuntu0.16.04.1, 74.0.1+build1-0ubuntu0.18.04.1, 74.0.1+build1-0ubuntu0.19.10.1
firefox-esr (Debian package) - addressed in versions 68.6.1esr-1~deb9u1, 68.6.1esr-1~deb10u1
thunderbird (Debian package) - addressed in versions 1:68.7.0-1~deb9u1, 1:68.7.0-1~deb10u1
Mozilla Thunderbird - update to 68.7.0
firefox (Alpine package) - update to 74.0.1-r0
thunderbird (Red Hat package) - addressed in versions 68.7.0-1.el6_10, 68.7.0-1.el7_8, 68.7.0-1.el8_0, 68.7.0-1.el8_1
firefox-esr (Alpine package) - update to 68.6.1-r0
thunderbird (Ubuntu package) - update to 1:68.7.0+build1-0ubuntu0.16.04.2
mozjs68 (Alpine package) - update to 68.7.0-r0
thunderbird (Alpine package) - update to 68.8.0-r0

External References

Related Security Bulletins