Red Hat Product Errata RHSA-2026:26268 - Security Advisory Issued: 2026-06-16 Updated: 2026-06-16 RHSA-2026:26268 - Security Advisory Overview Updated Packages Synopsis Important: thunderbird 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 thunderbird is now available for Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions and Red Hat Enterprise Linux 8.8 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. Description Mozilla Thunderbird is a standalone mail and newsgroup client. 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: Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component (CVE-2026-8959) 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 x86_64 - Extended Update Support Extension 8.8 x86_64 Red Hat Enterprise Linux Server - TUS 8.8 x86_64 Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 8.8 ppc64le Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 8.8 x86_64 Fixes BZ - 2476469 - CVE-2026-8388 firefox: thunderbird: Incorrect boundary conditions in the JavaScript Engine: JIT component BZ - 2476475 - CVE-2026-8391 firefox: thunderbird: Other issue in the JavaScript Engine component BZ - 2476492 - CVE-2026-8401 firefox: thunderbird: 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: thunderbird: 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: thunderbird: 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 - 2479861 - CVE-2026-8959 firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component BZ - 2479871 - CVE-2026-8961 firefox: Spoofing issue in the Form Autofill component BZ - 2479873 - CVE-2026-8947 firefox: thunderbird: 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-2026-8959 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 - Extended Update Support Extension 8.8 SRPM thunderbird-140.11.0-1.el8_8.src.rpm SHA-256: 83fd9626f598468f79c324d97c0aee99888861fcc07de9f387a7b7249c8a9bdf x86_64 thunderbird-140.11.0-1.el8_8.x86_64.rpm SHA-256: d65f31175e5decd6113e748a15816fc3c5c7edb2d5834d3a38177fa3c5d5f46c thunderbird-debuginfo-140.11.0-1.el8_8.x86_64.rpm SHA-256: 953c52fd5d1136fbaac8f6f6c03d776c93dfeb9f98b86d16ea7341908b094dc6 thunderbird-debugsource-140.11.0-1.el8_8.x86_64.rpm SHA-256: e57f0209df28abf367ccd13378ebbb5b2320d6374330c9b47ec2db29a744233c Red Hat Enterprise Linux Server - TUS 8.8 SRPM thunderbird-140.11.0-1.el8_8.src.rpm SHA-256: 83fd9626f598468f79c324d97c0aee99888861fcc07de9f387a7b7249c8a9bdf x86_64 thunderbird-140.11.0-1.el8_8.x86_64.rpm SHA-256: d65f31175e5decd6113e748a15816fc3c5c7edb2d5834d3a38177fa3c5d5f46c thunderbird-debuginfo-140.11.0-1.el8_8.x86_64.rpm SHA-256: 953c52fd5d1136fbaac8f6f6c03d776c93dfeb9f98b86d16ea7341908b094dc6 thunderbird-debugsource-140.11.0-1.el8_8.x86_64.rpm SHA-256: e57f0209df28abf367ccd13378ebbb5b2320d6374330c9b47ec2db29a744233c Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 8.8 SRPM thunderbird-140.11.0-1.el8_8.src.rpm SHA-256: 83fd9626f598468f79c324d97c0aee99888861fcc07de9f387a7b7249c8a9bdf ppc64le thunderbird-140.11.0-1.el8_8.ppc64le.rpm SHA-256: aa33fffa47f67803a05f11972f74776e0c2331e928cc4ad218fe37f572f05439 thunderbird-debuginfo-140.11.0-1.el8_8.ppc64le.rpm SHA-256: 5d9d0ca22c04f84d1cd081dc50cd97dd15fba05916f9c1f4025e983df90c6681 thunderbird-debugsource-140.11.0-1.el8_8.ppc64le.rpm SHA-256: 126e9c03bc81cd2591cef1217f431bcee4d5a84ca5b23e213726648e9558af6c Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 8.8 SRPM thunderbird-140.11.0-1.el8_8.src.rpm SHA-256: 83fd9626f598468f79c324d97c0aee99888861fcc07de9f387a7b7249c8a9bdf x86_64 thunderbird-140.11.0-1.el8_8.x86_64.rpm SHA-256: d65f31175e5decd6113e748a15816fc3c5c7edb2d5834d3a38177fa3c5d5f46c thunderbird-debuginfo-140.11.0-1.el8_8.x86_64.rpm SHA-256: 953c52fd5d1136fbaac8f6f6c03d776c93dfeb9f98b86d16ea7341908b094dc6 thunderbird-debugsource-140.11.0-1.el8_8.x86_64.rpm SHA-256: e57f0209df28abf367ccd13378ebbb5b2320d6374330c9b47ec2db29a744233c The Red Hat security contact is secalert@redhat.com . More contact details at https://access.redhat.com/security/team/contact/ .