Use-after-free in Firefox ESR and Mozilla Firefox - CVE-2020-26950

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Main Vulnerability Database Vulnerabilities #VU48235

Use-after-free in Firefox ESR and Mozilla Firefox - CVE-2020-26950

Published: November 9, 2020 / Updated: May 12, 2022


Vulnerability identifier: #VU48235
CSH Severity: High
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-2020-26950
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability: Public exploit is available

Vulnerability details

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a use-after-free error when processing HTML content, caused by MCallGetProperty opcode write side effects. A remote attacker can create a specially crafted web page, trick the victim into opening 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.


Affected software

Firefox ESR
Mozilla Firefox
Arch Linux
Gentoo Linux
Red Hat Enterprise Linux Workstation
Red Hat Enterprise Linux for Scientific Computing
Red Hat Enterprise Linux for Power, big endian
Red Hat Enterprise Linux Server
Red Hat Enterprise Linux Desktop
Red Hat Enterprise Linux for IBM z Systems
CentOS
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for ARM 64 - Extended Update Support
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 IBM z Systems - Extended Update Support
Red Hat Enterprise Linux Server - TUS
Slackware Linux
Ubuntu
openEuler
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 (Alpine package)
firefox-esr (Alpine package)
firefox (Red Hat package)
firefox-esr (Debian package)
thunderbird (Debian package)
thunderbird (Alpine package)
mozjs78 (Alpine package)
thunderbird (Red Hat package)
thunderbird (Ubuntu package)
firefox
firefox-debuginfo
firefox-debugsource
mozilla-crashreporter-firefox-debuginfo
firefox (Ubuntu package)
Mozilla Thunderbird

How to mitigate CVE-2020-26950

Install updates from vendor's website.

Firefox ESR - update to 78.4.1
Mozilla Firefox - update to 82.0.3
Mozilla Thunderbird - update to 78.4.2
firefox (Alpine package) - update to 82.0.3-r0
firefox-esr (Alpine package) - update to 78.5.0-r0
firefox (Red Hat package) - addressed in versions 78.4.1-1.el6_10, 78.4.1-1.el7_9, 78.4.1-1.el8_0, 78.4.1-1.el8_1, 78.4.1-1.el8_2, 78.4.1-1.el8_3
firefox-esr (Debian package) - update to 78.4.1esr-1~deb10u1
thunderbird (Debian package) - update to 78.4.2-1~deb10u1
thunderbird (Alpine package) - update to 78.5.1-r0
mozjs78 (Alpine package) - update to 78.4.1-r0
thunderbird (Red Hat package) - addressed in versions 78.4.3-1.el6_10, 78.4.3-1.el7_9, 78.4.3-1.el8_0, 78.4.3-1.el8_1, 78.4.3-1.el8_2, 78.4.3-1.el8_3
thunderbird (Ubuntu package) - update to 1:78.5.0+build3-0ubuntu0.20.10.1
firefox - update to 79.0-19
firefox-debuginfo - update to 79.0-19
firefox-debugsource - update to 79.0-19
mozilla-crashreporter-firefox-debuginfo - update to 79.0-19
firefox (Ubuntu package) - addressed in versions 82.0.3+build1-0ubuntu0.16.04.1, 82.0.3+build1-0ubuntu0.18.04.1, 82.0.3+build1-0ubuntu0.20.04.1, 82.0.3+build1-0ubuntu0.20.10.1

Links to Public Exploits and PoC-codes

External References

Related Security Bulletins