Red Hat alert RHSA-2026:15889-01 (thunderbird)

An update for thunderbird is now available for Red Hat Enterprise Linux 8.6
Advanced Mission Critical Update Support, Red Hat Enterprise Linux 8.6 Update
Services for SAP Solutions, and Red Hat Enterprise Linux 8.6
Telecommunications Update Service.

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.

Mozilla Thunderbird is a standalone mail and newsgroup client.

Security Fix(es):

* libpng: libpng: Arbitrary code execution due to use-after-free
vulnerability (CVE-2026-33416)

* libpng: libpng: Information disclosure and denial of service via
out-of-bounds read/write in Neon palette expansion (CVE-2026-33636)

* thunderbird: firefox: Memory safety bugs fixed in Firefox ESR 140.9.1,
Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2
(CVE-2026-5734)

* thunderbird: firefox: Memory safety bugs fixed in Firefox ESR 115.34.1,
Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird
149.0.2 (CVE-2026-5731)

* firefox: thunderbird: Incorrect boundary conditions, integer overflow in
the Graphics: Text component (CVE-2026-5732)

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.

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Original: https://access.redhat.com/security/data/csaf/v2/advisories/2026/rhsa-2026_15889.json