A Firefox security update has been released for Ubuntu Linux 18.04 LTS, 20.04 LTS, 20.10, and 21.04.

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Ubuntu Security Notice USN-4978-1
June 02, 2021

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

- Ubuntu 21.04
- Ubuntu 20.10
- Ubuntu 20.04 LTS
- Ubuntu 18.04 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 into opening a specially crafted website, an attacker could
potentially exploit these to cause a denial of service, re-enable
camera devices without an additional permission prompt, spoof the browser
UI, or execute arbitrary code. (CVE-2021-29959, CVE-2021-29961,
CVE-2021-29966, CVE-2021-29967)

It was discovered that filenames printed from private browsing mode were
incorrectly retained in preferences. A local attacker could potentially
exploit this to obtain sensitive information. (CVE-2021-29960)

Update instructions:

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

Ubuntu 21.04:
firefox 89.0+build2-0ubuntu0.21.04.1

Ubuntu 20.10:
firefox 89.0+build2-0ubuntu0.20.10.1

Ubuntu 20.04 LTS:
firefox 89.0+build2-0ubuntu0.20.04.2

Ubuntu 18.04 LTS:
firefox 89.0+build2-0ubuntu0.18.04.2

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

References:
  https://ubuntu.com/security/notices/USN-4978-1
CVE-2021-29959, CVE-2021-29960, CVE-2021-29961, CVE-2021-29966,
CVE-2021-29967

Package Information:
  https://launchpad.net/ubuntu/+source/firefox/89.0+build2-0ubuntu0.21.04.1
  https://launchpad.net/ubuntu/+source/firefox/89.0+build2-0ubuntu0.20.10.1
  https://launchpad.net/ubuntu/+source/firefox/89.0+build2-0ubuntu0.20.04.2
  https://launchpad.net/ubuntu/+source/firefox/89.0+build2-0ubuntu0.18.04.2