Red Hat Product Errata RHSA-2026:13977 - Security Advisory Issued: 2026-05-06 Updated: 2026-05-06 RHSA-2026:13977 - Security Advisory Overview Updated Packages Synopsis Important: firefox security update Type/Severity Security Advisory: Important Red Hat Lightspeed patch analysis Identify and remediate systems affected by this advisory. View affected systems 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): 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. Solution For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Affected Products Red Hat Enterprise Linux Server - Extended Life Cycle Support 7 x86_64 Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 7 s390x Red Hat Enterprise Linux Server - Extended Life Cycle Support for IBM Power, big endian 7 ppc64 Red Hat Enterprise Linux Server - Extended Life Cycle Support for IBM Power, little endian 7 ppc64le Fixes BZ - 2451805 - CVE-2026-33416 libpng: libpng: Arbitrary code execution due to use-after-free vulnerability BZ - 2451819 - CVE-2026-33636 libpng: libpng: Information disclosure and denial of service via out-of-bounds read/write in Neon palette expansion BZ - 2455897 - CVE-2026-5734 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 BZ - 2455901 - CVE-2026-5731 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 BZ - 2455908 - CVE-2026-5732 firefox: thunderbird: Incorrect boundary conditions, integer overflow in the Graphics: Text component RHEL-147877 - Firefox 140 ESR does not recognize CA certificates added to the system trust store CVEs CVE-2026-5731 CVE-2026-5732 CVE-2026-5734 CVE-2026-33416 CVE-2026-33636 References https://access.redhat.com/security/updates/classification/#important Note: More recent versions of these packages may be available. Click a package name for more details. Red Hat Enterprise Linux Server - Extended Life Cycle Support 7 SRPM firefox-140.9.1-2.el7_9.src.rpm SHA-256: 6334c53441a750c9ff7d5908bee52bb0e7a52e11029345d4021988fa566e97d4 x86_64 firefox-140.9.1-2.el7_9.x86_64.rpm SHA-256: 8a33112c73e5ab6ae2e1af52963d608b71c13af1ab7704a4353b37febedd9d6e Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 7 SRPM firefox-140.9.1-2.el7_9.src.rpm SHA-256: 6334c53441a750c9ff7d5908bee52bb0e7a52e11029345d4021988fa566e97d4 s390x firefox-140.9.1-2.el7_9.s390x.rpm SHA-256: 74d433f4b000ccb71a7f99f31dd30b643abe8d19147cea2a1e80c11cc8c76322 firefox-debuginfo-140.9.1-2.el7_9.s390x.rpm SHA-256: 4bb2a9671a5fadfb34bc5dd60581e21f850e9bf4b8b36d23adcd565bb5c418b6 Red Hat Enterprise Linux Server - Extended Life Cycle Support for IBM Power, big endian 7 SRPM firefox-140.9.1-2.el7_9.src.rpm SHA-256: 6334c53441a750c9ff7d5908bee52bb0e7a52e11029345d4021988fa566e97d4 ppc64 firefox-140.9.1-2.el7_9.ppc64.rpm SHA-256: ca333938d02a998a7ff8d2cfbf42c0ac1a72e6533d691f2893251e28ee69db1f firefox-debuginfo-140.9.1-2.el7_9.ppc64.rpm SHA-256: 280d024cc8804184190acafb1094d4be9917eacc1349d6d0e72859db3239fede Red Hat Enterprise Linux Server - Extended Life Cycle Support for IBM Power, little endian 7 SRPM firefox-140.9.1-2.el7_9.src.rpm SHA-256: 6334c53441a750c9ff7d5908bee52bb0e7a52e11029345d4021988fa566e97d4 ppc64le firefox-140.9.1-2.el7_9.ppc64le.rpm SHA-256: ce6878f5655076f4407680ec743cc58c99c8f285d4a5ba5a0102c019129913c5 firefox-debuginfo-140.9.1-2.el7_9.ppc64le.rpm SHA-256: 8c6021317d07eeee9c055f2f8139bf0a3e3d32f7a4b75730acc7602a7dabe8a5 The Red Hat security contact is secalert@redhat.com . More contact details at https://access.redhat.com/security/team/contact/ .