Another Firefox update has been released for Ubuntu Linux to address regressions introduced by the previous update

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Ubuntu Security Notice USN-3801-2
November 23, 2018

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

- Ubuntu 18.10
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

USN-3801-1 caused some minor regressions in Firefox.

Software Description:
- firefox: Mozilla Open Source web browser

Details:

USN-3801-1 fixed vulnerabilities in Firefox. The update introduced various
minor regressions. This update fixes the problems.

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 CSP
restrictions, spoof the protocol registration notification bar, leak
SameSite cookies, bypass mixed content warnings, or execute arbitrary
code. (CVE-2018-12388, CVE-2018-12390, CVE-2018-12392, CVE-2018-12393,
CVE-2018-12398, CVE-2018-12399, CVE-2018-12401, CVE-2018-12402,
CVE-2018-12403)

Multiple security issues were discovered with WebExtensions in Firefox.
If a user were tricked in to installing a specially crafted extension, an
attacker could potentially exploit these to bypass domain restrictions,
gain additional privileges, or run content scripts in local pages without
permission. (CVE-2018-12395, CVE-2018-12396, CVE-2018-12397)

Update instructions:

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

Ubuntu 18.10:
firefox 63.0.3+build1-0ubuntu0.18.10.1

Ubuntu 18.04 LTS:
firefox 63.0.3+build1-0ubuntu0.18.04.1

Ubuntu 16.04 LTS:
firefox 63.0.3+build1-0ubuntu0.16.04.1

Ubuntu 14.04 LTS:
firefox 63.0.3+build1-0ubuntu0.14.04.1

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

References:
https://usn.ubuntu.com/usn/usn-3801-2
https://usn.ubuntu.com/usn/usn-3801-1
https://launchpad.net/bugs/1804881

Package Information:
https://launchpad.net/ubuntu/+source/firefox/63.0.3+build1-0ubuntu0.18.10.1
https://launchpad.net/ubuntu/+source/firefox/63.0.3+build1-0ubuntu0.18.04.1
https://launchpad.net/ubuntu/+source/firefox/63.0.3+build1-0ubuntu0.16.04.1
https://launchpad.net/ubuntu/+source/firefox/63.0.3+build1-0ubuntu0.14.04.1

  Firefox Regression Update For Ubuntu