USN-4717-2: Firefox regression

08 February 2021

USN-4717-1 introduced a regression in Firefox.



  • firefox - Mozilla Open Source web browser


USN-4717-1 fixed vulnerabilities in Firefox. The update caused a
startup hang in some circumstances. 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, obtain sensitive
information, conduct clickjacking attacks, or execute arbitrary code.

Update instructions

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

Ubuntu 20.10
Ubuntu 20.04
Ubuntu 18.04
Ubuntu 16.04

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