RHSA-2021:4134 — Security Advisory

Red Hat Security Advisory: thunderbird security update

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Severity

Important

Red Hat Product Security

RHEL 7

Products

Official CSAF product identity

Published · November 5, 2021

Updated · June 25, 2026

Topic

An update for thunderbird is now available for Red Hat Enterprise Linux 7.

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.

Description

Mozilla Thunderbird is a standalone mail and newsgroup client.

This update upgrades Thunderbird to version 91.3.0.

Security Fix(es):

  • Mozilla: Use-after-free in HTTP2 Session object

  • Mozilla: Memory safety bugs fixed in Firefox 94 and Firefox ESR 91.3

  • Mozilla: iframe sandbox rules did not apply to XSLT stylesheets (CVE-2021-38503)

  • Mozilla: Use-after-free in file picker dialog (CVE-2021-38504)

  • Mozilla: Firefox could be coaxed into going into fullscreen mode without notification or warning (CVE-2021-38506)

  • Mozilla: Opportunistic Encryption in HTTP2 could be used to bypass the Same-Origin-Policy on services hosted on other ports (CVE-2021-38507)

  • Mozilla: Permission Prompt could be overlaid, resulting in user confusion and potential spoofing (CVE-2021-38508)

  • Mozilla: Javascript alert box could have been spoofed onto an arbitrary domain (CVE-2021-38509)

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.

Related CVEs

RHSA-2021:4134 — Red Hat Security Advisory: thunderbird security update | PulseLinux