Red Hat Product Errata RHSA-2026:26174 - Security Advisory Issued: 2026-06-16 Updated: 2026-06-16 RHSA-2026:26174 - 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 9.4 Update Services for SAP Solutions. 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 Server - AUS 9.4 x86_64 Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.4 ppc64le Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 9.4 x86_64 Red Hat Enterprise Linux for ARM 64 - 4 years of updates 9.4 aarch64 Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 9.4 s390x Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 9.4 x86_64 Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 9.4 aarch64 Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 9.4 ppc64le Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 9.4 s390x 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 Server - AUS 9.4 SRPM thunderbird-140.11.0-1.el9_4.src.rpm SHA-256: 6756d9f1f7a1e61fa8bb3c06f189ccde2d0f213b455376c3ab90608e916d1780 x86_64 thunderbird-140.11.0-1.el9_4.x86_64.rpm SHA-256: 6093a42136de19832c7439528bdb329eac5300ab39f2cc0514795eb83b5470fc thunderbird-debuginfo-140.11.0-1.el9_4.x86_64.rpm SHA-256: 98497b2a24f62d7eccd0cc87589b5046e6aca8f7721399b04d9988cbd2295c06 thunderbird-debugsource-140.11.0-1.el9_4.x86_64.rpm SHA-256: 7dcc5a44e331bcf0ef26e56ced339bc5a3600c40a5af1f392c6c99e59a61f19c Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.4 SRPM thunderbird-140.11.0-1.el9_4.src.rpm SHA-256: 6756d9f1f7a1e61fa8bb3c06f189ccde2d0f213b455376c3ab90608e916d1780 ppc64le thunderbird-140.11.0-1.el9_4.ppc64le.rpm SHA-256: 2ca0bb10e84a770776c8bd0b1fa3f0000c159fca34bc0b5b6c3d45e869d3a608 thunderbird-debuginfo-140.11.0-1.el9_4.ppc64le.rpm SHA-256: 5f5f78e967dd71004078df40bd0260feb8a28aa0d7e79349eb0d27b63d703d65 thunderbird-debugsource-140.11.0-1.el9_4.ppc64le.rpm SHA-256: 26c144131e72179726f7c06e2007c02052209e1092b530399c8599d550ed9aa0 Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 9.4 SRPM thunderbird-140.11.0-1.el9_4.src.rpm SHA-256: 6756d9f1f7a1e61fa8bb3c06f189ccde2d0f213b455376c3ab90608e916d1780 x86_64 thunderbird-140.11.0-1.el9_4.x86_64.rpm SHA-256: 6093a42136de19832c7439528bdb329eac5300ab39f2cc0514795eb83b5470fc thunderbird-debuginfo-140.11.0-1.el9_4.x86_64.rpm SHA-256: 98497b2a24f62d7eccd0cc87589b5046e6aca8f7721399b04d9988cbd2295c06 thunderbird-debugsource-140.11.0-1.el9_4.x86_64.rpm SHA-256: 7dcc5a44e331bcf0ef26e56ced339bc5a3600c40a5af1f392c6c99e59a61f19c Red Hat Enterprise Linux for ARM 64 - 4 years of updates 9.4 SRPM thunderbird-140.11.0-1.el9_4.src.rpm SHA-256: 6756d9f1f7a1e61fa8bb3c06f189ccde2d0f213b455376c3ab90608e916d1780 aarch64 thunderbird-140.11.0-1.el9_4.aarch64.rpm SHA-256: 1e11dd6804a15f62a04c0dd5fcfd129a9ccf46a1e1fd36221410bfc1efe1a198 thunderbird-debuginfo-140.11.0-1.el9_4.aarch64.rpm SHA-256: f80e219c04f19e963f5f953e8f682f1950c31b2c86cf36f9ae4593bff7876357 thunderbird-debugsource-140.11.0-1.el9_4.aarch64.rpm SHA-256: 151677dd7683afeabadb98d31377722c2fc2f2cc00bb50aaf2443e5cf2cabb9c Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 9.4 SRPM thunderbird-140.11.0-1.el9_4.src.rpm SHA-256: 6756d9f1f7a1e61fa8bb3c06f189ccde2d0f213b455376c3ab90608e916d1780 s390x thunderbird-140.11.0-1.el9_4.s390x.rpm SHA-256: 94865b9125eb6f6692f0ebb2a222a517da411d7a6ffbd431643ff31e4912644c thunderbird-debuginfo-140.11.0-1.el9_4.s390x.rpm SHA-256: b015e16cab088d97a988431c5d04cabea5f9fa08c3bb93ae21289b24819c2795 thunderbird-debugsource-140.11.0-1.el9_4.s390x.rpm SHA-256: eaaf716703ff41357324562d3af2700ff9add4ce62ba2900970cc2d54030a8a5 Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 9.4 SRPM thunderbird-140.11.0-1.el9_4.src.rpm SHA-256: 6756d9f1f7a1e61fa8bb3c06f189ccde2d0f213b455376c3ab90608e916d1780 x86_64 thunderbird-140.11.0-1.el9_4.x86_64.rpm SHA-256: 6093a42136de19832c7439528bdb329eac5300ab39f2cc0514795eb83b5470fc thunderbird-debuginfo-140.11.0-1.el9_4.x86_64.rpm SHA-256: 98497b2a24f62d7eccd0cc87589b5046e6aca8f7721399b04d9988cbd2295c06 thunderbird-debugsource-140.11.0-1.el9_4.x86_64.rpm SHA-256: 7dcc5a44e331bcf0ef26e56ced339bc5a3600c40a5af1f392c6c99e59a61f19c Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 9.4 SRPM thunderbird-140.11.0-1.el9_4.src.rpm SHA-256: 6756d9f1f7a1e61fa8bb3c06f189ccde2d0f213b455376c3ab90608e916d1780 aarch64 thunderbird-140.11.0-1.el9_4.aarch64.rpm SHA-256: 1e11dd6804a15f62a04c0dd5fcfd129a9ccf46a1e1fd36221410bfc1efe1a198 thunderbird-debuginfo-140.11.0-1.el9_4.aarch64.rpm SHA-256: f80e219c04f19e963f5f953e8f682f1950c31b2c86cf36f9ae4593bff7876357 thunderbird-debugsource-140.11.0-1.el9_4.aarch64.rpm SHA-256: 151677dd7683afeabadb98d31377722c2fc2f2cc00bb50aaf2443e5cf2cabb9c Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 9.4 SRPM thunderbird-140.11.0-1.