A Thunderbird 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-5168-2
December 01, 2021

thunderbird vulnerability
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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:

Thunderbird could be made to crash or run programs if it verified a
specially crafted signature.

Software Description:
- thunderbird: Mozilla Open Source mail and newsgroup client

Details:

Tavis Ormandy discovered that NSS, included with Thunderbird, incorrectly
handled verifying DSA/RSA-PSS signatures. A remote attacker could use this
issue to cause Thunderbird to crash, resulting in a denial of service, or
possibly execute arbitrary code.

Update instructions:

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

Ubuntu 21.10:
thunderbird 1:91.3.1+build1-0ubuntu0.21.10.2

Ubuntu 21.04:
thunderbird 1:78.14.0+build1-0ubuntu0.21.04.2

Ubuntu 20.04 LTS:
thunderbird 1:78.14.0+build1-0ubuntu0.20.04.2

Ubuntu 18.04 LTS:
thunderbird 1:78.14.0+build1-0ubuntu0.18.04.2

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

References:
  https://ubuntu.com/security/notices/USN-5168-2
  https://ubuntu.com/security/notices/USN-5168-1
CVE-2021-43527

Package Information:
  https://launchpad.net/ubuntu/+source/thunderbird/1:91.3.1+build1-0ubuntu0.21.10.2
  https://launchpad.net/ubuntu/+source/thunderbird/1:78.14.0+build1-0ubuntu0.21.04.2
  https://launchpad.net/ubuntu/+source/thunderbird/1:78.14.0+build1-0ubuntu0.20.04.2
  https://launchpad.net/ubuntu/+source/thunderbird/1:78.14.0+build1-0ubuntu0.18.04.2