Use-after-free in Mozilla Firefox - CVE-2019-9821
Published: May 21, 2019
Vulnerability identifier: #VU18555
CSH Severity: High
CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2019-9821
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to compromise vulnerable system.
The vulnerability exists due to a use-after-free error in AssertWorkerThread due to a race condition with shared workers. A remote attacker can create a specially crafted web page, trick the victim into visiting it, trigger use-after-free error and execute arbitrary code on the target system.
Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable system.
Affected software
Mozilla Firefox
Arch Linux
Opensuse
firefox (Ubuntu package)
Arch Linux
Opensuse
firefox (Ubuntu package)
How to mitigate CVE-2019-9821
Install updates from vendor's website.
Mozilla Firefox - update to 67.0
firefox (Ubuntu package) - addressed in versions 67.0+build2-0ubuntu0.16.04.1, 67.0+build2-0ubuntu0.18.04.1, 67.0+build2-0ubuntu0.18.10.1, 67.0+build2-0ubuntu0.19.04.1, 67.0.1+build1-0ubuntu0.16.04.1, 67.0.1+build1-0ubuntu0.18.04.1, 67.0.1+build1-0ubuntu0.18.10.1, 67.0.1+build1-0ubuntu0.19.04.1, 67.0.2+build2-0ubuntu0.16.04.1, 67.0.2+build2-0ubuntu0.18.04.1, 67.0.2+build2-0ubuntu0.18.10.1, 67.0.2+build2-0ubuntu0.19.04.1
firefox (Ubuntu package) - addressed in versions 67.0+build2-0ubuntu0.16.04.1, 67.0+build2-0ubuntu0.18.04.1, 67.0+build2-0ubuntu0.18.10.1, 67.0+build2-0ubuntu0.19.04.1, 67.0.1+build1-0ubuntu0.16.04.1, 67.0.1+build1-0ubuntu0.18.04.1, 67.0.1+build1-0ubuntu0.18.10.1, 67.0.1+build1-0ubuntu0.19.04.1, 67.0.2+build2-0ubuntu0.16.04.1, 67.0.2+build2-0ubuntu0.18.04.1, 67.0.2+build2-0ubuntu0.18.10.1, 67.0.2+build2-0ubuntu0.19.04.1