A Firefox security update has been released for Ubuntu Linux 18.04 LTS, 20.04 LTS, 21.04, and 21.10.

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Ubuntu Security Notice USN-5131-1
November 03, 2021

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

- Ubuntu 21.10
- Ubuntu 21.04
- 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, bypass security
restrictions, spoof the browser UI, confuse the user, conduct phishing
attacks, or execute arbitrary code. (CVE-2021-38503, CVE-2021-38504,
CVE-2021-38506, CVE-2021-38507, CVE-2021-38508, CVE-2021-38509)

It was discovered that the 'Copy Image Link' context menu action
would copy the final image URL after redirects. If a user were tricked
into copying and pasting a link for an embedded image that triggered
authentication flows back to the page, an attacker could potentially
exploit this to steal authentication tokens.

Update instructions:

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

Ubuntu 21.10:
firefox 94.0+build3-0ubuntu0.21.10.1

Ubuntu 21.04:
firefox 94.0+build3-0ubuntu0.21.04.1

Ubuntu 20.04 LTS:
firefox 94.0+build3-0ubuntu0.20.04.1

Ubuntu 18.04 LTS:
firefox 94.0+build3-0ubuntu0.18.04.1

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

References:
  https://ubuntu.com/security/notices/USN-5131-1
CVE-2021-38503, CVE-2021-38504, CVE-2021-38506, CVE-2021-38507,
CVE-2021-38508, CVE-2021-38509

Package Information:
  https://launchpad.net/ubuntu/+source/firefox/94.0+build3-0ubuntu0.21.10.1
  https://launchpad.net/ubuntu/+source/firefox/94.0+build3-0ubuntu0.21.04.1
  https://launchpad.net/ubuntu/+source/firefox/94.0+build3-0ubuntu0.20.04.1
  https://launchpad.net/ubuntu/+source/firefox/94.0+build3-0ubuntu0.18.04.1