Security restrictions bypass in Mozilla Firefox - CVE-2021-29959
Published: June 1, 2021
Vulnerability identifier: #VU53713
CSH Severity: Medium
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2021-29959
CWE-ID: CWE-264
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass implemented security restrictions.
The vulnerability exists due to the way user is prompted to access microphone and camera by the website. When a user has already allowed a website to access microphone and camera, disabling camera sharing would not fully prevent the website from re-enabling it without an additional prompt. This was only possible if the website kept recording with the microphone until re-enabling the camera.
Affected software
Mozilla Firefox
Arch Linux
Gentoo Linux
Ubuntu
firefox (Ubuntu package)
Arch Linux
Gentoo Linux
Ubuntu
firefox (Ubuntu package)
How to mitigate CVE-2021-29959
Install updates from vendor's website.
Mozilla Firefox - update to 89.0
firefox (Ubuntu package) - addressed in versions 89.0+build2-0ubuntu0.18.04.2, 89.0+build2-0ubuntu0.20.04.2, 89.0+build2-0ubuntu0.20.10.1, 89.0+build2-0ubuntu0.21.04.1
firefox (Ubuntu package) - addressed in versions 89.0+build2-0ubuntu0.18.04.2, 89.0+build2-0ubuntu0.20.04.2, 89.0+build2-0ubuntu0.20.10.1, 89.0+build2-0ubuntu0.21.04.1