RHSA-2026:99111 - Security Advisory

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: thunderbird: Use-after-free in the JavaScript: GC component (CVE-2026-118007)
• firefox: thunderbird: Sandbox escape due to use-after-free in the XPCOM component (CVE-2026-118021)
• firefox: thunderbird: Use-after-free in the Graphics: Text component (CVE-2026-118024)
• firefox: thunderbird: Race condition, use-after-free in the DOM: File component (CVE-2026-118019)
• firefox: thunderbird: Use-after-free in the Audio/Video component (CVE-2026-124860)
• firefox: thunderbird: Site isolation issue in the DOM: Navigation component (CVE-2026-124914)
• firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-124869)
• firefox: thunderbird: Privilege escalation in the DOM: Navigation component (CVE-2026-124854)
• firefox: thunderbird: Use-after-free in the Layout: Positioned component (CVE-2026-124877)
• firefox: thunderbird: Sandbox escape due to use-after-free in the Widget: Gtk component (CVE-2026-124917)
• firefox: thunderbird: Incorrect boundary conditions in the DOM: Selection component (CVE-2026-124891)
• firefox: thunderbird: Use-after-free in the Graphics: Canvas2D component (CVE-2026-124857)
• firefox: thunderbird: Information disclosure in the Security: RLBox component (CVE-2026-124941)
• firefox: thunderbird: Sandbox escape in the DOM: Navigation component (CVE-2026-124855)
• firefox: thunderbird: Spoofing issue in the Security component (CVE-2026-124934)
• firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics: Text component (CVE-2026-124853)
• firefox: thunderbird: Sandbox escape in the DOM: Navigation component (CVE-2026-124905)
• firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Storage: Cache API component (CVE-2026-124859)
• firefox: thunderbird: Use-after-free in the CSS Parsing and Computation component (CVE-2026-124881)
• firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-124862)
• firefox: thunderbird: Use-after-free in the CSS Parsing and Computation component (CVE-2026-124882)
• firefox: thunderbird: Information disclosure in the Private Browsing component (CVE-2026-124909)
• firefox: thunderbird: Use-after-free in the CSS Parsing and Computation component (CVE-2026-124876)
• firefox: thunderbird: Use-after-free in the DOM: Workers component (CVE-2026-124893)
• firefox: thunderbird: Use-after-free in the Graphics: WebRender component (CVE-2026-124906)
• firefox: thunderbird: Incorrect boundary conditions in the Layout: Text and Fonts component (CVE-2026-124887)
• firefox: thunderbird: Mitigation bypass in the WebExtensions component (CVE-2026-124910)
• firefox: thunderbird: Privilege escalation in the Nimbus Desktop Client component (CVE-2026-124951)
• firefox: thunderbird: Use-after-free in the Audio/Video component (CVE-2026-124865)
• firefox: thunderbird: Incorrect boundary conditions, use-after-free in the Graphics component (CVE-2026-124948)
• firefox: thunderbird: Undefined behavior in the WebRTC: Networking component (CVE-2026-124935)
• firefox: thunderbird: Incorrect boundary conditions in the DOM: CSS Object Model component (CVE-2026-124875)
• firefox: thunderbird: Sandbox escape due to use-after-free in the IPC component (CVE-2026-124903)
• firefox: thunderbird: Incorrect boundary conditions in the Networking: HTTP component (CVE-2026-124856)
• firefox: thunderbird: Use-after-free in the Networking: Cookies component (CVE-2026-124894)
• firefox: thunderbird: Use-after-free in the Storage: localStorage & sessionStorage component (CVE-2026-124895)
• firefox: thunderbird: Use-after-free in the Graphics: Text component (CVE-2026-124885)
• firefox: thunderbird: Use-after-free in the Layout: Text and Fonts component (CVE-2026-124899)
• firefox: thunderbird: Sandbox escape in the Console component (CVE-2026-124933)
• firefox: thunderbird: Use-after-free in the Layout component (CVE-2026-124866)
• firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-124883)
• firefox: thunderbird: Information disclosure in the Layout: Form Controls component (CVE-2026-124929)
• firefox: thunderbird: Incorrect boundary conditions in the JavaScript: GC component (CVE-2026-124870)
• firefox: thunderbird: Site isolation issue in the Graphics: WebRender component (CVE-2026-124927)
• firefox: thunderbird: Incorrect boundary conditions in the Graphics: WebGPU component (CVE-2026-124915)
• firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-124890)
• firefox: thunderbird: Information disclosure in the Address Bar component (CVE-2026-124930)
• firefox: thunderbird: Invalid pointer in the Layout: Text and Fonts component (CVE-2026-124886)
• firefox: thunderbird: Use-after-free in the DOM: HTML Parser component (CVE-2026-124858)
• firefox: thunderbird: Privilege escalation, sandbox escape due to use-after-free in the Graphics: CanvasWebGL component (CVE-2026-124907)
• firefox: thunderbird: Invalid pointer in the DOM: Editor component (CVE-2026-124873)
• firefox: thunderbird: Spoofing issue in the DOM: Security component (CVE-2026-124912)
• firefox: thunderbird: Same-origin policy bypass in the Networking: HTTP component (CVE-2026-124874)
• firefox: thunderbird: Use-after-free in the JavaScript: GC component (CVE-2026-124892)
• firefox: thunderbird: Invalid pointer in the DOM: Streams component (CVE-2026-124942)
• firefox: thunderbird: Use-after-free in the CSS Transitions and Animations component (CVE-2026-124922)
• firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: WebRender component (CVE-2026-124918)
• firefox: thunderbird: Use-after-free in the JavaScript: GC component (CVE-2026-124884)
• firefox: thunderbird: Incorrect boundary conditions in the DOM: Core & HTML component (CVE-2026-124868)
• firefox: thunderbird: Privilege escalation due to use-after-free in the WebRTC: Networking component (CVE-2026-124919)
• firefox: thunderbird: Incorrect boundary conditions in the Graphics: WebRender component (CVE-2026-124924)
• firefox: thunderbird: Same-origin policy bypass due to race condition in the Audio/Video component (CVE-2026-124902)
• firefox: thunderbird: Invalid pointer in the Networking: Cache component (CVE-2026-124879)
• firefox: thunderbird: Use-after-free in the Graphics component (CVE-2026-124932)
• firefox: thunderbird: Mitigation bypass in the File Handling component (CVE-2026-124940)
• firefox: thunderbird: Same-origin policy bypass in the DOM: Core & HTML component (CVE-2026-124931)
• firefox: thunderbird: Incorrect boundary conditions in the WebRTC component (CVE-2026-124926)
• firefox: thunderbird: Use-after-free in the DOM: HTML Parser component (CVE-2026-124863)
• firefox: thunderbird: Use-after-free in the CSS Parsing and Computation component (CVE-2026-124889)
• firefox: thunderbird: Site isolation issue in the Networking component (CVE-2026-124913)
• firefox: thunderbird: Use-after-free in the JavaScript: GC component (CVE-2026-124897)
• firefox: thunderbird: Sandbox escape due to use-after-free in the DOM: Service Workers component (CVE-2026-124864)
• firefox: thunderbird: Use-after-free in the Cycle Collector component (CVE-2026-124872)
• firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-124880)
• firefox: thunderbird: Invalid pointer in the Layout: Text and Fonts component (CVE-2026-124896)
• firefox: thunderbird: Other issue in the Networking: JAR component (CVE-2026-124901)
• firefox: thunderbird: Incorrect boundary conditions in the Layout: Text and Fonts component (CVE-2026-124888)
• firefox: thunderbird: Mitigation bypass in the Add-ons Manager component (CVE-2026-124938)
• firefox: thunderbird: Sandbox escape due to use-after-free in the Audio/Video: cubeb component (CVE-2026-124861)
• firefox: thunderbird: Use-after-free in the DOM: Editor component (CVE-2026-124898)
• firefox: thunderbird: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-124939)

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 9 x86_64
• Red Hat Enterprise Linux for IBM z Systems 9 s390x
• Red Hat Enterprise Linux for Power, little endian 9 ppc64le
• Red Hat Enterprise Linux for ARM 64 9 aarch64

Fixes

• BZ - 2562015 - CVE-2026-118007 firefox: thunderbird: Use-after-free in the JavaScript: GC component
• BZ - 2562042 - CVE-2026-118021 firefox: thunderbird: Sandbox escape due to use-after-free in the XPCOM component
• BZ - 2562122 - CVE-2026-118024 firefox: thunderbird: Use-after-free in the Graphics: Text component
• BZ - 2562259 - CVE-2026-118019 firefox: thunderbird: Race condition, use-after-free in the DOM: File component
• BZ - 2569830 - CVE-2026-124860 firefox: thunderbird: Use-after-free in the Audio/Video component
• BZ - 2569846 - CVE-2026-124914 firefox: thunderbird: Site isolation issue in the DOM: Navigation component
• BZ - 2569877 - CVE-2026-124869 firefox: thunderbird: Use-after-free in the DOM: Core & HTML component
• BZ - 2569907 - CVE-2026-124854 firefox: thunderbird: Privilege escalation in the DOM: Navigation component
• BZ - 2569955 - CVE-2026-124877 firefox: thunderbird: Use-after-free in the Layout: Positioned component
• BZ - 2569957 - CVE-2026-124917 firefox: thunderbird: Sandbox escape due to use-after-free in the Widget: Gtk component
• BZ - 2569970 - CVE-2026-124891 firefox: thunderbird: Incorrect boundary conditions in the DOM: Selection component
• BZ - 2569978 - CVE-2026-124857 firefox: thunderbird: Use-after-free in the Graphics: Canvas2D component
• BZ - 2569982 - CVE-2026-124941 firefox: thunderbird: Information disclosure in the Security: RLBox component
• BZ - 2569985 - CVE-2026-124855 firefox: thunderbird: Sandbox escape in the DOM: Navigation component
• BZ - 2569994 - CVE-2026-124934 firefox: thunderbird: Spoofing issue in the Security component
• BZ - 2570012 - CVE-2026-124853 firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics: Text component
• BZ - 2570014 - CVE-2026-124905 firefox: thunderbird: Sandbox escape in the DOM: Navigation component
• BZ - 2570100 - CVE-2026-124859 firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Storage: Cache API component
• BZ - 2570107 - CVE-2026-124881 firefox: thunderbird: Use-after-free in the CSS Parsing and Computation component
• BZ - 2570116 - CVE-2026-124862 firefox: thunderbird: Use-after-free in the DOM: Core & HTML component
• BZ - 2570127 - CVE-2026-124882 firefox: thunderbird: Use-after-free in the CSS Parsing and Computation component
• BZ - 2570137 - CVE-2026-124909 firefox: thunderbird: Information disclosure in the Private Browsing component
• BZ - 2570140 - CVE-2026-124876 firefox: thunderbird: Use-after-free in the CSS Parsing and Computation component
• BZ - 2570149 - CVE-2026-124893 firefox: thunderbird: Use-after-free in the DOM: Workers component
• BZ - 2570165 - CVE-2026-124906 firefox: thunderbird: Use-after-free in the Graphics: WebRender component
• BZ - 2570172 - CVE-2026-124887 firefox: thunderbird: Incorrect boundary conditions in the Layout: Text and Fonts component
• BZ - 2570208 - CVE-2026-124910 firefox: thunderbird: Mitigation bypass in the WebExtensions component
• BZ - 2570241 - CVE-2026-124951 firefox: thunderbird: Privilege escalation in the Nimbus Desktop Client component
• BZ - 2570248 - CVE-2026-124865 firefox: thunderbird: Use-after-free in the Audio/Video component
• BZ - 2570255 - CVE-2026-124948 firefox: thunderbird: Incorrect boundary conditions, use-after-free in the Graphics component
• BZ - 2570306 - CVE-2026-124935 firefox: thunderbird: Undefined behavior in the WebRTC: Networking component
• BZ - 2570334 - CVE-2026-124875 firefox: thunderbird: Incorrect boundary conditions in the DOM: CSS Object Model component
• BZ - 2570365 - CVE-2026-124903 firefox: thunderbird: Sandbox escape due to use-after-free in the IPC component
• BZ - 2570417 - CVE-2026-124856 firefox: thunderbird: Incorrect boundary conditions in the Networking: HTTP component
• BZ - 2570433 - CVE-2026-124894 firefox: thunderbird: Use-after-free in the Networking: Cookies component
• BZ - 2570440 - CVE-2026-124895 firefox: thunderbird: Use-after-free in the Storage: localStorage & sessionStorage component
• BZ - 2570491 - CVE-2026-124885 firefox: thunderbird: Use-after-free in the Graphics: Text component
• BZ - 2570514 - CVE-2026-124899 firefox: thunderbird: Use-after-free in the Layout: Text and Fonts component
• BZ - 2570521 - CVE-2026-124933 firefox: thunderbird: Sandbox escape in the Console component
• BZ - 2570548 - CVE-2026-124866 firefox: thunderbird: Use-after-free in the Layout component
• BZ - 2570574 - CVE-2026-124883 firefox: thunderbird: Use-after-free in the DOM: Core & HTML component
• BZ - 2570589 - CVE-2026-124929 firefox: thunderbird: Information disclosure in the Layout: Form Controls component
• BZ - 2570601 - CVE-2026-124870 firefox: thunderbird: Incorrect boundary conditions in the JavaScript: GC component
• BZ - 2570629 - CVE-2026-124927 firefox: thunderbird: Site isolation issue in the Graphics: WebRender component
• BZ - 2570636 - CVE-2026-124915 firefox: thunderbird: Incorrect boundary conditions in the Graphics: WebGPU component
• BZ - 2570644 - CVE-2026-124890 firefox: thunderbird: Use-after-free in the DOM: Core & HTML component
• BZ - 2570655 - CVE-2026-124930 firefox: thunderbird: Information disclosure in the Address Bar component
• BZ - 2570660 - CVE-2026-124886 firefox: thunderbird: Invalid pointer in the Layout: Text and Fonts component
• BZ - 2570662 - CVE-2026-124858 firefox: thunderbird: Use-after-free in the DOM: HTML Parser component
• BZ - 2570664 - CVE-2026-124907 firefox: thunderbird: Privilege escalation, sandbox escape due to use-after-free in the Graphics: CanvasWebGL component
• BZ - 2570686 - CVE-2026-124873 firefox: thunderbird: Invalid pointer in the DOM: Editor component
• BZ - 2570704 - CVE-2026-124912 firefox: thunderbird: Spoofing issue in the DOM: Security component
• BZ - 2570705 - CVE-2026-124874 firefox: thunderbird: Same-origin policy bypass in the Networking: HTTP component
• BZ - 2570717 - CVE-2026-124892 firefox: thunderbird: Use-after-free in the JavaScript: GC component
• BZ - 2570726 - CVE-2026-124942 firefox: thunderbird: Invalid pointer in the DOM: Streams component
• BZ - 2570740 - CVE-2026-124922 firefox: thunderbird: Use-after-free in the CSS Transitions and Animations component
• BZ - 2570753 - CVE-2026-124918 firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: WebRender component
• BZ - 2570755 - CVE-2026-124884 firefox: thunderbird: Use-after-free in the JavaScript: GC component
• BZ - 2570770 - CVE-2026-124868 firefox: thunderbird: Incorrect boundary conditions in the DOM: Core & HTML component
• BZ - 2570787 - CVE-2026-124919 firefox: thunderbird: Privilege escalation due to use-after-free in the WebRTC: Networking component
• BZ - 2570811 - CVE-2026-124924 firefox: thunderbird: Incorrect boundary conditions in the Graphics: WebRender component
• BZ - 2570824 - CVE-2026-124902 firefox: thunderbird: Same-origin policy bypass due to race condition in the Audio/Video component
• BZ - 2570865 - CVE-2026-124879 firefox: thunderbird: Invalid pointer in the Networking: Cache component
• BZ - 2570876 - CVE-2026-124932 firefox: thunderbird: Use-after-free in the Graphics component
• BZ - 2570896 - CVE-2026-124940 firefox: thunderbird: Mitigation bypass in the File Handling component
• BZ - 2570942 - CVE-2026-124931 firefox: thunderbird: Same-origin policy bypass in the DOM: Core & HTML component
• BZ - 2570955 - CVE-2026-124926 firefox: thunderbird: Incorrect boundary conditions in the WebRTC component
• BZ - 2571008 - CVE-2026-124863 firefox: thunderbird: Use-after-free in the DOM: HTML Parser component
• BZ - 2571031 - CVE-2026-124889 firefox: thunderbird: Use-after-free in the CSS Parsing and Computation component
• BZ - 2571052 - CVE-2026-124913 firefox: thunderbird: Site isolation issue in the Networking component
• BZ - 2571076 - CVE-2026-124897 firefox: thunderbird: Use-after-free in the JavaScript: GC component
• BZ - 2571102 - CVE-2026-124864 firefox: thunderbird: Sandbox escape due to use-after-free in the DOM: Service Workers component
• BZ - 2571104 - CVE-2026-124872 firefox: thunderbird: Use-after-free in the Cycle Collector component
• BZ - 2571112 - CVE-2026-124880 firefox: thunderbird: Use-after-free in the DOM: Core & HTML component
• BZ - 2571117 - CVE-2026-124896 firefox: thunderbird: Invalid pointer in the Layout: Text and Fonts component
• BZ - 2571125 - CVE-2026-124901 firefox: thunderbird: Other issue in the Networking: JAR component
• BZ - 2571126 - CVE-2026-124888 firefox: thunderbird: Incorrect boundary conditions in the Layout: Text and Fonts component
• BZ - 2571146 - CVE-2026-124938 firefox: thunderbird: Mitigation bypass in the Add-ons Manager component
• BZ - 2571152 - CVE-2026-124861 firefox: thunderbird: Sandbox escape due to use-after-free in the Audio/Video: cubeb component
• BZ - 2571158 - CVE-2026-124898 firefox: thunderbird: Use-after-free in the DOM: Editor component
• BZ - 2571162 - CVE-2026-124939 firefox: thunderbird: JIT miscompilation in the JavaScript Engine: JIT component

CVEs

• CVE-2026-118007
• CVE-2026-118019
• CVE-2026-118021
• CVE-2026-118024
• CVE-2026-124853
• CVE-2026-124854
• CVE-2026-124855
• CVE-2026-124856
• CVE-2026-124857
• CVE-2026-124858
• CVE-2026-124859
• CVE-2026-124860
• CVE-2026-124861
• CVE-2026-124862
• CVE-2026-124863
• CVE-2026-124864
• CVE-2026-124865
• CVE-2026-124866
• CVE-2026-124868
• CVE-2026-124869
• CVE-2026-124870
• CVE-2026-124872
• CVE-2026-124873
• CVE-2026-124874
• CVE-2026-124875
• CVE-2026-124876
• CVE-2026-124877
• CVE-2026-124879
• CVE-2026-124880
• CVE-2026-124881
• CVE-2026-124882
• CVE-2026-124883
• CVE-2026-124884
• CVE-2026-124885
• CVE-2026-124886
• CVE-2026-124887
• CVE-2026-124888
• CVE-2026-124889
• CVE-2026-124890
• CVE-2026-124891
• CVE-2026-124892
• CVE-2026-124893
• CVE-2026-124894
• CVE-2026-124895
• CVE-2026-124896
• CVE-2026-124897
• CVE-2026-124898
• CVE-2026-124899
• CVE-2026-124901
• CVE-2026-124902
• CVE-2026-124903
• CVE-2026-124905
• CVE-2026-124906
• CVE-2026-124907
• CVE-2026-124909
• CVE-2026-124910
• CVE-2026-124912
• CVE-2026-124913
• CVE-2026-124914
• CVE-2026-124915
• CVE-2026-124917
• CVE-2026-124918
• CVE-2026-124919
• CVE-2026-124922
• CVE-2026-124924
• CVE-2026-124926
• CVE-2026-124927
• CVE-2026-124929
• CVE-2026-124930
• CVE-2026-124931
• CVE-2026-124932
• CVE-2026-124933
• CVE-2026-124934
• CVE-2026-124935
• CVE-2026-124938
• CVE-2026-124939
• CVE-2026-124940
• CVE-2026-124941
• CVE-2026-124942
• CVE-2026-124948
• CVE-2026-124951

References

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