A Firefox security update has been released for Ubuntu Linux 19.10, 18.04 LTS, and 16.04 LTS.

USN-4323-1: Firefox vulnerabilities

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Ubuntu Security Notice USN-4323-1
April 07, 2020

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

- Ubuntu 19.10
- 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:

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, or execute arbitrary code. (CVE-2020-6821, CVE-2020-6822,
CVE-2020-6824, CVE-2020-6825, CVE-2020-6826)

It was discovered that extensions could obtain auth codes from OAuth login
flows in some circumstances. If a user were tricked in to installing a
specially crafted extension, an attacker could potentially exploit this to
obtain access to the user's account. (CVE-2020-6823)

Update instructions:

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

Ubuntu 19.10:
firefox 75.0+build3-0ubuntu0.19.10.1

Ubuntu 18.04 LTS:
firefox 75.0+build3-0ubuntu0.18.04.1

Ubuntu 16.04 LTS:
firefox 75.0+build3-0ubuntu0.16.04.1

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

References:
  https://usn.ubuntu.com/4323-1
CVE-2020-6821, CVE-2020-6822, CVE-2020-6823, CVE-2020-6824,
CVE-2020-6825, CVE-2020-6826

Package Information:
  https://launchpad.net/ubuntu/+source/firefox/75.0+build3-0ubuntu0.19.10.1
  https://launchpad.net/ubuntu/+source/firefox/75.0+build3-0ubuntu0.18.04.1
  https://launchpad.net/ubuntu/+source/firefox/75.0+build3-0ubuntu0.16.04.1