RHSA-2026:58898 - Security Advisory

Topic

An update for firefox is now available for Red Hat Enterprise Linux 8.

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: thunderbird: Mitigation bypass in the Data Loss Prevention component (CVE-2026-74983)
• 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: Use-after-free in the Graphics: ImageLib component (CVE-2026-74943)
• firefox: thunderbird: Information disclosure in the DOM: UI Events & Focus Handling component (CVE-2026-74971)
• firefox: thunderbird: Privilege escalation in the Graphics: CanvasWebGL component (CVE-2026-74941)
• firefox: Privilege escalation in the Shell Integration component (CVE-2026-74965)
• firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component (CVE-2026-74946)
• firefox: Race condition, use-after-free in the Graphics component (CVE-2026-74973)
• firefox: thunderbird: Privilege escalation due to use-after-free in the Graphics: Canvas2D component (CVE-2026-74949)
• 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: Use-after-free in the Graphics: Text component (CVE-2026-74940)
• firefox: thunderbird: Site isolation issue in the WebExtensions component (CVE-2026-74960)
• firefox: thunderbird: Use-after-free in the Layout: Text and Fonts component (CVE-2026-74969)
• 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: thunderbird: Same-origin policy bypass in the Audio/Video: Playback component (CVE-2026-74967)
• 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: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-74944)
• 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 8 x86_64
• Red Hat Enterprise Linux for IBM z Systems 8 s390x
• Red Hat Enterprise Linux for Power, little endian 8 ppc64le
• Red Hat Enterprise Linux for ARM 64 8 aarch64
• Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 8.10 x86_64
• Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 8.10 aarch64
• Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 8.10 ppc64le
• Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 8.10 s390x

Fixes

• BZ - 2517819 - CVE-2026-74983 firefox: thunderbird: Mitigation bypass in the Data Loss Prevention component
• 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 - 2517826 - CVE-2026-74943 firefox: thunderbird: Use-after-free in the Graphics: ImageLib component
• BZ - 2517831 - CVE-2026-74971 firefox: thunderbird: Information disclosure in the DOM: UI Events & Focus Handling component
• BZ - 2517833 - CVE-2026-74941 firefox: thunderbird: Privilege escalation in the Graphics: CanvasWebGL component
• BZ - 2517834 - CVE-2026-74965 firefox: Privilege escalation in the Shell Integration component
• BZ - 2517835 - CVE-2026-74946 firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component
• BZ - 2517836 - CVE-2026-74973 firefox: Race condition, use-after-free in the Graphics component
• BZ - 2517837 - CVE-2026-74949 firefox: thunderbird: Privilege escalation due to use-after-free in the Graphics: Canvas2D 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 - 2517841 - CVE-2026-74940 firefox: thunderbird: Use-after-free in the Graphics: Text component
• BZ - 2517845 - CVE-2026-74960 firefox: thunderbird: Site isolation issue in the WebExtensions component
• BZ - 2517846 - CVE-2026-74969 firefox: thunderbird: Use-after-free in the Layout: Text and Fonts 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 - 2517858 - CVE-2026-74967 firefox: thunderbird: Same-origin policy bypass in the Audio/Video: Playback 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 - 2517868 - CVE-2026-74944 firefox: thunderbird: Use-after-free in the DOM: Core & HTML 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-2026-74940
• CVE-2026-74941
• CVE-2026-74942
• CVE-2026-74943
• CVE-2026-74944
• CVE-2026-74945
• CVE-2026-74946
• CVE-2026-74948
• CVE-2026-74949
• CVE-2026-74953
• CVE-2026-74957
• CVE-2026-74959
• CVE-2026-74960
• CVE-2026-74962
• CVE-2026-74963
• CVE-2026-74964
• CVE-2026-74965
• CVE-2026-74967
• CVE-2026-74969
• CVE-2026-74971
• CVE-2026-74972
• CVE-2026-74973
• CVE-2026-74974
• CVE-2026-74976
• CVE-2026-74983
• CVE-2026-74987
• CVE-2026-74990

References

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