RHSA-2026:65633 - Security Advisory

Topic

An update for thunderbird is now available for Red Hat Enterprise Linux 10.0 Extended Update 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 Thunderbird is a standalone mail and newsgroup client.

Security Fix(es):

• firefox: thunderbird: Site isolation issue in the Graphics: CanvasWebGL component (CVE-2026-74934)
• firefox: thunderbird: Privilege escalation in the Networking: Cookies component (CVE-2026-74953)
• firefox: thunderbird: Internally found bugs fixed in Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154 (CVE-2026-74987)
• firefox: thunderbird: Information disclosure in the Graphics component (CVE-2026-74948)
• firefox: thunderbird: Information disclosure in the DOM: UI Events & Focus Handling component (CVE-2026-74971)
• firefox: Race condition, use-after-free in the Graphics component (CVE-2026-74973)
• firefox: thunderbird: Internally found bugs fixed in Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154 (CVE-2026-74990)
• firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-74936)
• firefox: thunderbird: Site isolation issue in the WebExtensions component (CVE-2026-74960)
• firefox: thunderbird: Mitigation bypass in the Storage: Cache API component (CVE-2026-74959)
• firefox: thunderbird: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-74976)
• firefox: thunderbird: Same-origin policy bypass in the Graphics: ImageLib component (CVE-2026-74974)
• firefox: thunderbird: Mitigation bypass in the Safe Browsing component (CVE-2026-74957)
• firefox: Privilege escalation in the Remote Settings Client component (CVE-2026-74942)
• firefox: thunderbird: Privilege escalation in the DOM: Navigation component (CVE-2026-74939)
• firefox: thunderbird: Information disclosure in the DOM: Push Subscriptions component (CVE-2026-74972)
• firefox: thunderbird: Information disclosure in the Graphics: Text component (CVE-2026-74945)
• firefox: thunderbird: Same-origin policy bypass in the Networking: Cookies component (CVE-2026-74963)
• firefox: Integer overflow in the Graphics component (CVE-2026-74964)
• firefox: Site isolation issue in the Networking: Cookies component (CVE-2026-74962)
• firefox: thunderbird: Privilege escalation in the DOM: Networking component (CVE-2026-74935)

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 10.0 x86_64
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 10.0 s390x
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 10.0 ppc64le
• Red Hat Enterprise Linux for ARM 64 - Extended Update Support 10.0 aarch64
• Red Hat Enterprise Linux for ARM 64 - 4 years of updates 10.0 aarch64
• Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 10.0 s390x
• Red Hat Enterprise Linux for Power, little endian - 4 years of support 10.0 ppc64le
• Red Hat Enterprise Linux for x86_64 - 4 years of updates 10.0 x86_64

Fixes

• BZ - 2517820 - CVE-2026-74934 firefox: thunderbird: Site isolation issue in the Graphics: CanvasWebGL component
• BZ - 2517822 - CVE-2026-74953 firefox: thunderbird: Privilege escalation in the Networking: Cookies component
• BZ - 2517823 - CVE-2026-74987 firefox: thunderbird: Internally found bugs fixed in Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154
• BZ - 2517825 - CVE-2026-74948 firefox: thunderbird: Information disclosure in the Graphics component
• BZ - 2517831 - CVE-2026-74971 firefox: thunderbird: Information disclosure in the DOM: UI Events & Focus Handling component
• BZ - 2517836 - CVE-2026-74973 firefox: Race condition, use-after-free in the Graphics component
• BZ - 2517839 - CVE-2026-74990 firefox: thunderbird: Internally found bugs fixed in Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154
• BZ - 2517840 - CVE-2026-74936 firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component
• BZ - 2517845 - CVE-2026-74960 firefox: thunderbird: Site isolation issue in the WebExtensions component
• BZ - 2517849 - CVE-2026-74959 firefox: thunderbird: Mitigation bypass in the Storage: Cache API component
• BZ - 2517851 - CVE-2026-74976 firefox: thunderbird: JIT miscompilation in the JavaScript Engine: JIT component
• BZ - 2517853 - CVE-2026-74974 firefox: thunderbird: Same-origin policy bypass in the Graphics: ImageLib component
• BZ - 2517856 - CVE-2026-74957 firefox: thunderbird: Mitigation bypass in the Safe Browsing component
• BZ - 2517859 - CVE-2026-74942 firefox: Privilege escalation in the Remote Settings Client component
• BZ - 2517860 - CVE-2026-74939 firefox: thunderbird: Privilege escalation in the DOM: Navigation component
• BZ - 2517862 - CVE-2026-74972 firefox: thunderbird: Information disclosure in the DOM: Push Subscriptions component
• BZ - 2517863 - CVE-2026-74945 firefox: thunderbird: Information disclosure in the Graphics: Text component
• BZ - 2517866 - CVE-2026-74963 firefox: thunderbird: Same-origin policy bypass in the Networking: Cookies component
• BZ - 2517870 - CVE-2026-74964 firefox: Integer overflow in the Graphics component
• BZ - 2517872 - CVE-2026-74962 firefox: Site isolation issue in the Networking: Cookies component
• BZ - 2517874 - CVE-2026-74935 firefox: thunderbird: Privilege escalation in the DOM: Networking component

CVEs

• CVE-2026-74934
• CVE-2026-74935
• CVE-2026-74936
• CVE-2026-74939
• CVE-2026-74942
• CVE-2026-74945
• CVE-2026-74948
• CVE-2026-74953
• CVE-2026-74957
• CVE-2026-74959
• CVE-2026-74960
• CVE-2026-74962
• CVE-2026-74963
• CVE-2026-74964
• CVE-2026-74971
• CVE-2026-74972
• CVE-2026-74973
• CVE-2026-74974
• CVE-2026-74976
• CVE-2026-74987
• CVE-2026-74990

References

• https://access.redhat.com/security/updates/classification/#important