A Firefox regression update has been released for Ubuntu Linux 18.04 LTS, 20.04 LTS, and 21.04.

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Ubuntu Security Notice USN-5037-2
August 25, 2021

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

- Ubuntu 21.04
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

USN-5037-1 caused a regression in Firefox.

Software Description:
- firefox: Mozilla Open Source web browser

Details:

USN-5037-1 fixed vulnerabilities in Firefox. The update introduced a
regression that caused Firefox to repeatedly prompt for a password. 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 into opening a specially crafted website, an attacker could
potentially exploit these to cause a denial of service, obtain sensitive
information, trick a user into accepting unwanted permissions, or execute
arbitrary code.

Update instructions:

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

Ubuntu 21.04:
firefox 91.0.2+build1-0ubuntu0.21.04.1

Ubuntu 20.04 LTS:
firefox 91.0.2+build1-0ubuntu0.20.04.1

Ubuntu 18.04 LTS:
firefox 91.0.2+build1-0ubuntu0.18.04.1

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

References:
  https://ubuntu.com/security/notices/USN-5037-2
  https://ubuntu.com/security/notices/USN-5037-1
  https://launchpad.net/bugs/1941496

Package Information:

  https://launchpad.net/ubuntu/+source/firefox/91.0.2+build1-0ubuntu0.21.04.1

  https://launchpad.net/ubuntu/+source/firefox/91.0.2+build1-0ubuntu0.20.04.1

  https://launchpad.net/ubuntu/+source/firefox/91.0.2+build1-0ubuntu0.18.04.1