Red Hat Product Errata RHSA-2026:21378 - Security Advisory Issued: 2026-05-27 Updated: 2026-05-27 RHSA-2026:21378 - 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 9. 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): firefox: Incorrect boundary conditions in the JavaScript Engine: JIT component (CVE-2026-8388) firefox: Other issue in the JavaScript Engine component (CVE-2026-8391) firefox: Sandbox escape in the Profile Backup component (CVE-2026-8401) firefox: Integer overflow in the Networking: JAR component (CVE-2026-8956) firefox: Memory safety bugs fixed in Firefox ESR 115.36, Firefox ESR 140.11 and Firefox 151 (CVE-2026-8975) firefox: Privilege escalation in the DOM: Workers component (CVE-2026-8955) firefox: Denial-of-service due to invalid pointer in the Audio/Video: Web Codecs component (CVE-2026-8968) firefox: Incorrect boundary conditions, integer overflow in the Audio/Video component (CVE-2026-8954) firefox: Information disclosure, sandbox escape in the Security: Process Sandboxing component (CVE-2026-8958) firefox: Incorrect boundary conditions in the Audio/Video: Web Codecs component (CVE-2026-8946) firefox: Privilege escalation in the Security component (CVE-2026-8970) firefox: Same-origin policy bypass in the Networking: HTTP component (CVE-2026-8950) firefox: Memory safety bugs fixed in Firefox ESR 140.11 and Firefox 151 (CVE-2026-8974) firefox: Sandbox escape due to use-after-free in the Disability Access APIs component (CVE-2026-8953) firefox: Spoofing issue in the Form Autofill component (CVE-2026-8961) firefox: Use-after-free in the DOM: Bindings (WebIDL) component (CVE-2026-8947) firefox: Mitigation bypass in the DOM: Security component (CVE-2026-8962) firefox: Privilege escalation in the Enterprise Policies component (CVE-2026-8957) 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 for IBM z Systems 9 s390x Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 9.8 s390x Red Hat Enterprise Linux for Power, little endian 9 ppc64le Red Hat Enterprise Linux for Power, little endian - Extended Update Support 9.8 ppc64le Red Hat Enterprise Linux for ARM 64 9 aarch64 Red Hat Enterprise Linux for ARM 64 - Extended Update Support 9.8 aarch64 Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.8 ppc64le Red Hat Enterprise Linux for ARM 64 - 4 years of updates 9.8 aarch64 Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 9.8 s390x Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 9.8 aarch64 Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 9.8 ppc64le Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 9.8 s390x Fixes BZ - 2476469 - CVE-2026-8388 firefox: Incorrect boundary conditions in the JavaScript Engine: JIT component BZ - 2476475 - CVE-2026-8391 firefox: Other issue in the JavaScript Engine component BZ - 2476492 - CVE-2026-8401 firefox: Sandbox escape in the Profile Backup component BZ - 2479839 - CVE-2026-8956 firefox: Integer overflow in the Networking: JAR component BZ - 2479840 - CVE-2026-8975 firefox: Memory safety bugs fixed in Firefox ESR 115.36, Firefox ESR 140.11 and Firefox 151 BZ - 2479842 - CVE-2026-8955 firefox: Privilege escalation in the DOM: Workers component BZ - 2479846 - CVE-2026-8968 firefox: Denial-of-service due to invalid pointer in the Audio/Video: Web Codecs component BZ - 2479847 - CVE-2026-8954 firefox: Incorrect boundary conditions, integer overflow in the Audio/Video component BZ - 2479848 - CVE-2026-8958 firefox: Information disclosure, sandbox escape in the Security: Process Sandboxing component BZ - 2479849 - CVE-2026-8946 firefox: Incorrect boundary conditions in the Audio/Video: Web Codecs component BZ - 2479852 - CVE-2026-8970 firefox: Privilege escalation in the Security component BZ - 2479853 - CVE-2026-8950 firefox: Same-origin policy bypass in the Networking: HTTP component BZ - 2479855 - CVE-2026-8974 firefox: Memory safety bugs fixed in Firefox ESR 140.11 and Firefox 151 BZ - 2479860 - CVE-2026-8953 firefox: Sandbox escape due to use-after-free in the Disability Access APIs component BZ - 2479871 - CVE-2026-8961 firefox: Spoofing issue in the Form Autofill component BZ - 2479873 - CVE-2026-8947 firefox: Use-after-free in the DOM: Bindings (WebIDL) component BZ - 2479876 - CVE-2026-8962 firefox: Mitigation bypass in the DOM: Security component BZ - 2479880 - CVE-2026-8957 firefox: Privilege escalation in the Enterprise Policies component CVEs CVE-2026-8388 CVE-2026-8391 CVE-2026-8401 CVE-2026-8946 CVE-2026-8947 CVE-2026-8950 CVE-2026-8953 CVE-2026-8954 CVE-2026-8955 CVE-2026-8956 CVE-2026-8957 CVE-2026-8958 CVE-2026-8961 CVE-2026-8962 CVE-2026-8968 CVE-2026-8970 CVE-2026-8974 CVE-2026-8975 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 for x86_64 9 SRPM x86_64 firefox-debuginfo-140.11.0-1.el9_8.x86_64.rpm SHA-256: dc90174de915f28ec1b6025637c7977752b55a7798a25f2d110fc170095d41ce firefox-debugsource-140.11.0-1.el9_8.x86_64.rpm SHA-256: 35daa03f644bc606e17ff31e7ebe1928451f86732d3e6d2d1808bf652ec7edcd Red Hat Enterprise Linux for IBM z Systems 9 SRPM firefox-140.11.0-1.el9_8.src.rpm SHA-256: 71b3fe91f8061197ce1a7f8da01acf7f16bf2e5bed4315be53bd00983aeb6afc s390x firefox-140.11.0-1.el9_8.s390x.rpm SHA-256: afc10aef6c99be903aad49097348ddfb77a6565201efd2c449a66b5aa3dfe4b2 firefox-debuginfo-140.11.0-1.el9_8.s390x.rpm SHA-256: f90703d7a3ad21dc29b404b725a8bb892f361bdfd2bc3fab6074ca086cd6c9bf firefox-debugsource-140.11.0-1.el9_8.s390x.rpm SHA-256: 8a4d70f640a9f07a9f132a262d70a2211475f4c57f6d3c1776df4a1df3d55425 firefox-x11-140.11.0-1.el9_8.s390x.rpm SHA-256: 13d15051bd4ee2237414238b934a2b649bb160e6125a8c48bc0ce42f4bea9788 Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 9.8 SRPM firefox-140.11.0-1.el9_8.src.rpm SHA-256: 71b3fe91f8061197ce1a7f8da01acf7f16bf2e5bed4315be53bd00983aeb6afc s390x firefox-140.11.0-1.el9_8.s390x.rpm SHA-256: afc10aef6c99be903aad49097348ddfb77a6565201efd2c449a66b5aa3dfe4b2 firefox-debuginfo-140.11.0-1.el9_8.s390x.rpm SHA-256: f90703d7a3ad21dc29b404b725a8bb892f361bdfd2bc3fab6074ca086cd6c9bf firefox-debugsource-140.11.0-1.el9_8.s390x.rpm SHA-256: 8a4d70f640a9f07a9f132a262d70a2211475f4c57f6d3c1776df4a1df3d55425 firefox-x11-140.11.0-1.el9_8.s390x.rpm SHA-256: 13d15051bd4ee2237414238b934a2b649bb160e6125a8c48bc0ce42f4bea9788 Red Hat Enterprise Linux for Power, little endian 9 SRPM firefox-140.11.0-1.el9_8.src.rpm SHA-256: 71b3fe91f8061197ce1a7f8da01acf7f16bf2e5bed4315be53bd00983aeb6afc ppc64le firefox-140.11.0-1.el9_8.ppc64le.rpm SHA-256: 29c81bedb4f1b6db34a35027bc15ad6803705d226664b2df0f0ba2b4aaff25e1 firefox-debuginfo-140.11.0-1.el9_8.ppc64le.rpm SHA-256: 5529326c0ec8c8232851016dc5e477d4c9540e79387096159c9966d14d9479e5 firefox-debugsource-140.11.0-1.el9_8.ppc64le.rpm SHA-256: c691a26b7bb815a5d25dfcf71b2ac9c1c9dbae30fcbe50e18a29dac4d5d12600 firefox-x11-140.11.0-1.el9_8.ppc64le.rpm SHA-256: b571dc9cdaf67ac1c380758ba09c5f1fc7309c3b293ff8c3651f2825a45f9e2e Red Hat Enterprise Linux for Power, little endian - Extended Update Support 9.8 SRPM firefox-140.11.0-1.el9_8.src.rpm SHA-256: 71b3fe91f8061197ce1a7f8da01acf7f16bf2e5bed4315be53bd00983aeb6afc ppc64le firefox-140.11.0-1.el9_8.ppc64le.rpm SHA-256: 29c81bedb4f1b6db34a35027bc15ad6803705d226664b2df0f0ba2b4aaff25e1 firefox-debuginfo-140.11.0-1.el9_8.ppc64le.rpm SHA-256: 5529326c0ec8c8232851016dc5e477d4c9540e79387096159c9966d14d9479e5 firefox-debugsource-140.11.0-1.el9_8.ppc64le.rpm SHA-256: c691a26b7bb815a5d25dfcf71b2ac9c1c9dbae30fcbe50e18a29dac4d5d12600 firefox-x11-140.11.0-1.el9_8.ppc64le.rpm SHA-256: b571dc9cdaf67ac1c380758ba09c5f1fc7309c3b293ff8c3651f2825a45f9e2e Red Hat Enterprise Linux for ARM 64 9 SRPM firefox-140.11.0-1.el9_8.src.rpm SHA-256: 71b3fe91f8061197ce1a7f8da01acf7f16bf2e5bed4315be53bd00983aeb6afc aarch64 firefox-140.11.0-1.el9_8.aarch64.rpm SHA-256: 24d7b00289040a4546880fcb737492aba8c513ef2fefe6f7516569fdb60ecaa2 firefox-debuginfo-140.11.0-1.el9_8.aarch64.rpm SHA-256: f8d9147cfd6597503ed2a6ccdb2b8ee192b6252492b22a30a6c2edc4f54b3e0d firefox-debugsource-140.11.0-1.el9_8.aarch64.rpm SHA-256: cc99ff5f46dfd63be89401f77be4a7f9dde639643418a8712d41fd68e5532c2a firefox-x11-140.11.0-1.el9_8.aarch64.rpm SHA-256: 6589158092684eea890cfbfc7d350173c3a9e4eca694179640260c6b2c447ccd Red Hat Enterprise Linux for ARM 64 - Extended Update Support 9.8 SRPM firefox-140.11.0-1.el9_8.src.rpm SHA-256: 71b3fe91f8061197ce1a7f8da01acf7f16bf2e5bed4315be53bd00983aeb6afc aarch64 firefox-140.11.0-1.el9_8.aarch64.rpm SHA-256: 24d7b00289040a4546880fcb737492aba8c513ef2fefe6f7516569fdb60ecaa2 firefox-debuginfo-140.11.0-1.el9_8.aarch64.rpm SHA-256: f8d9147cfd6597503ed2a6ccdb2b8ee192b6252492b22a30a6c2edc4f54b3e0d firefox-debugsource-140.11.0-1.el9_8.aarch64.rpm SHA-256: cc99ff5f46dfd63be89401f77be4a7f9dde639643418a8712d41fd68e5532c2a firefox-x11-140.11.0-1.el9_8.aarch64.rpm SHA-256: 65891580