USN-4353-2: Firefox regression

12 May 2020

USN-4353-1 caused a regression in Firefox.



  • firefox - Mozilla Open Source web browser


USN-4353-1 fixed vulnerabilities in Firefox. The update caused a
regression that impaired the functionality of some addons. This update
fixes the problem.

We apologize for the inconvenience.

Original advisory details:

Multiple security issues were discovered in Firefox. If a user were
tricked in to opening a specially crafted website, an attacker could
potentially exploit these to cause a denial of service, bypass security
restrictions, spoof the URL bar, or execute arbitrary code.
(CVE-2020-6831, CVE-2020-12387, CVE-2020-12390, CVE-2020-12391,
CVE-2020-12394, CVE-2020-12395, CVE-2020-12396)

It was discovered that the Devtools’ ‘Copy as cURL’ feature did not
properly HTTP POST data of a request. If a user were tricked in to using
the ‘Copy as cURL’ feature to copy and paste a command with specially
crafted data in to a terminal, an attacker could potentially exploit this
to obtain sensitive information from local files.

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 20.04
Ubuntu 19.10
Ubuntu 18.04
Ubuntu 16.04

After a standard system update you need to restart Firefox to make
all the necessary changes.