A Firefox security update has been released for Ubuntu 16.04 LTS, 18.04 LTS, 20.04 LTS and 20.10.

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Ubuntu Security Notice USN-4687-1
January 08, 2021

firefox vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.10
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Firefox could be made to crash or run programs as your login if it
opened a malicious website.

Software Description:
- firefox: Mozilla Open Source web browser

Details:

A use-after-free was discovered in Firefox when handling SCTP packets.
An attacker could potentially exploit this to cause a denial of service,
or execute arbitrary code.

Update instructions:

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

Ubuntu 20.10:
firefox 84.0.2+build1-0ubuntu0.20.10.1

Ubuntu 20.04 LTS:
firefox 84.0.2+build1-0ubuntu0.20.04.1

Ubuntu 18.04 LTS:
firefox 84.0.2+build1-0ubuntu0.18.04.1

Ubuntu 16.04 LTS:
firefox 84.0.2+build1-0ubuntu0.16.04.1

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

References:
  https://usn.ubuntu.com/4687-1
CVE-2020-16044

Package Information:

  https://launchpad.net/ubuntu/+source/firefox/84.0.2+build1-0ubuntu0.20.10.1

  https://launchpad.net/ubuntu/+source/firefox/84.0.2+build1-0ubuntu0.20.04.1

  https://launchpad.net/ubuntu/+source/firefox/84.0.2+build1-0ubuntu0.18.04.1

  https://launchpad.net/ubuntu/+source/firefox/84.0.2+build1-0ubuntu0.16.04.1