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

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Ubuntu Security Notice USN-4701-1
January 20, 2021

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

- Ubuntu 20.10

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 in to opening a specially crafted website in a browsing context,
an attacker could potentially exploit these to cause a denial of service,
obtain sensitive information, bypass the CSS sanitizer, or execute
arbitrary code. (CVE-2020-16042, CVE-2020-16044, CVE-2020-26971,
CVE-2020-26973, CVE-2020-26974, CVE-2020-26978, CVE-2020-35113)

It was discovered that the proxy.onRequest API did not catch
view-source URLs. If a user were tricked in to installing an
extension with the proxy permission and opening View Source, an
attacker could potentially exploit this to obtain sensitive
information. (CVE-2020-35111)

A stack overflow was discovered due to incorrect parsing of SMTP server
response codes. An attacker could potentially exploit this to execute
arbitrary code. (CVE-2020-26970)

Update instructions:

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

Ubuntu 20.10:
thunderbird 1:78.6.1+build1-0ubuntu0.20.10.1

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

References:
  https://usn.ubuntu.com/4701-1
CVE-2020-16042, CVE-2020-16044, CVE-2020-26970, CVE-2020-26971,
CVE-2020-26973, CVE-2020-26974, CVE-2020-26978, CVE-2020-35111,
CVE-2020-35113

Package Information:

  https://launchpad.net/ubuntu/+source/thunderbird/1:78.6.1+build1-0ubuntu0.20.10.1