Red Hat Security Advisory
Synopsis: Important: thunderbird security update
Advisory ID: RHSA-2021:0995-01
Product: Red Hat Enterprise Linux
Advisory URL: https://access.redhat.com/errata/RHSA-2021:0995
Issue date: 2021-03-25
CVE Names: CVE-2021-23981 CVE-2021-23982 CVE-2021-23984
An update for thunderbird is now available for Red Hat Enterprise Linux 8.1
Extended Update Support.
Red Hat Product Security has rated this update as having a security impact
of Important. A Common Vulnerability Scoring System (CVSS) base score,
which gives a detailed severity rating, is available for each vulnerability
from the CVE link(s) in the References section.
2. Relevant releases/architectures:
Red Hat Enterprise Linux AppStream EUS (v. 8.1) – ppc64le, x86_64
Mozilla Thunderbird is a standalone mail and newsgroup client.
This update upgrades Thunderbird to version 78.9.0.
* Mozilla: Texture upload into an unbound backing buffer resulted in an
out-of-bound read (CVE-2021-23981)
* Mozilla: Memory safety bugs fixed in Firefox 87 and Firefox ESR 78.9
* Mozilla: Internal network hosts could have been probed by a malicious
* Mozilla: Malicious extensions could have spoofed popup information
For more details about the security issue(s), including the impact, a CVSS
score, acknowledgments, and other related information, refer to the CVE
page(s) listed in the References section.
For details on how to apply this update, which includes the changes
described in this advisory, refer to:
All running instances of Thunderbird must be restarted for the update to
5. Bugs fixed (https://bugzilla.redhat.com/):
1942783 – CVE-2021-23981 Mozilla: Texture upload into an unbound backing buffer resulted in an out-of-bound read
1942785 – CVE-2021-23982 Mozilla: Internal network hosts could have been probed by a malicious webpage
1942786 – CVE-2021-23984 Mozilla: Malicious extensions could have spoofed popup information
1942787 – CVE-2021-23987 Mozilla: Memory safety bugs fixed in Firefox 87 and Firefox ESR 78.9
6. Package List:
Red Hat Enterprise Linux AppStream EUS (v. 8.1):
These packages are GPG signed by Red Hat for security. Our key and
details on how to verify the signature are available from
The Red Hat security contact is
details at https://access.redhat.com/security/team/contact/
Copyright 2021 Red Hat, Inc.
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