A Thunderbird security update has been released for Ubuntu Linux 20.04 LTS and 20.10.

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Ubuntu Security Notice USN-4936-1
May 06, 2021

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

- Ubuntu 20.10
- Ubuntu 20.04 LTS

Summary:

Several security issues were fixed in Thunderbird.

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

Details:

Multiple security issues were discovered in Thunderbird. If a user were
tricked into opening a specially crafted website in a browsing context,
an attacker could potentially exploit these to cause a denial of service,
obtain sensitive information, or execute arbitrary code. (CVE-2021-23968,
CVE-2021-23969, CVE-2021-23973, CVE-2021-23978)

It was discovered that Thunderbird may keep key material in memory in some
circumstances. A local attacker could potentially exploit this to obtain
private keys. (CVE-2021-29950)

Update instructions:

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

Ubuntu 20.10:
thunderbird 1:78.8.1+build1-0ubuntu0.20.10.1

Ubuntu 20.04 LTS:
thunderbird 1:78.8.1+build1-0ubuntu0.20.04.1

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

References:
  https://ubuntu.com/security/notices/USN-4936-1
CVE-2021-23968, CVE-2021-23969, CVE-2021-23973, CVE-2021-23978,
CVE-2021-29950

Package Information:

  https://launchpad.net/ubuntu/+source/thunderbird/1:78.8.1+build1-0ubuntu0.20.10.1

  https://launchpad.net/ubuntu/+source/thunderbird/1:78.8.1+build1-0ubuntu0.20.04.1