RHSA-2026:13977 — Security Advisory
Red Hat Security Advisory: firefox security update
Severity
ImportantRed Hat Product Security
Products
Official CSAF product identity
Published · May 6, 2026
Updated · October 31, 2026
Topic
An update for firefox is now available for Red Hat Enterprise Linux 7 Extended Lifecycle 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.
Description
Mozilla Firefox is an open-source web browser, designed for standards compliance, performance, and portability.
Security Fix(es):
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libpng: libpng: Arbitrary code execution due to use-after-free vulnerability (CVE-2026-33416)
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libpng: libpng: Information disclosure and denial of service via out-of-bounds read/write in Neon palette expansion (CVE-2026-33636)
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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)
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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)
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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.