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OpenAdvisories
Critical RHSA-2026:65110 31 CVEs

Red Hat Security Advisory: firefox security update

Published Sep 9, 2026 · Updated Sep 15, 2026

Ecosystem: Red Hat

Fixed packages 6

ReleasePackageFixed in
Red Hat · RHEL 8.6 AUS rhel_aus:8.6::appstream firefox 0:140.14.0-1.el8_6
Red Hat · RHEL 8.6 AUS rhel_aus:8.6::appstream firefox-debuginfo 0:140.14.0-1.el8_6
Red Hat · RHEL 8.6 AUS rhel_aus:8.6::appstream firefox-debugsource 0:140.14.0-1.el8_6
Red Hat · RHEL 8.6 EUS Long Life rhel_eus_long_life:8.6::appstream firefox 0:140.14.0-1.el8_6
Red Hat · RHEL 8.6 EUS Long Life rhel_eus_long_life:8.6::appstream firefox-debuginfo 0:140.14.0-1.el8_6
Red Hat · RHEL 8.6 EUS Long Life rhel_eus_long_life:8.6::appstream firefox-debugsource 0:140.14.0-1.el8_6

Vulnerabilities 31

  • Critical 9.8
    CVE-2026-74936 Public exploit

    Use-after-free in the JavaScript: WebAssembly component

    Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Critical 9.8
    CVE-2026-74940

    Use-after-free in the Graphics: Text component

    Use-after-free in the Graphics: Text component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Critical 9.8
    CVE-2026-74943 Public exploit

    Use-after-free in the Graphics: ImageLib component

    Use-after-free in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Critical 9.8
    CVE-2026-74944

    Use-after-free in the DOM: Core & HTML component

    Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Critical 9.8
    CVE-2026-74964

    Integer overflow in the Graphics component

    Integer overflow in the Graphics component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Critical 9.8
    CVE-2026-74987

    Internally found bugs fixed in Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154

    Internally found bugs present in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited.…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Critical 9.8
    CVE-2026-74990

    Internally found bugs fixed in Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154

    Internally found bugs present in Firefox ESR 115.38, Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could …

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Critical 9.1
    CVE-2026-74959

    Mitigation bypass in the Storage: Cache API component

    Mitigation bypass in the Storage: Cache API component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-74935

    Privilege escalation in the DOM: Networking component

    Privilege escalation in the DOM: Networking component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-74939 Public exploit

    Privilege escalation in the DOM: Navigation component

    Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-74941

    Privilege escalation in the Graphics: CanvasWebGL component

    Privilege escalation in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-74942

    Privilege escalation in the Remote Settings Client component

    Privilege escalation in the Remote Settings Client component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-74946

    Information disclosure due to incorrect boundary conditions in the Graphics: CanvasWebGL component

    Information disclosure due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 15…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-74949

    Use-after-free in the Graphics: Canvas2D component

    Use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-74953

    Privilege escalation in the Networking: Cookies component

    Privilege escalation in the Networking: Cookies component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-74965

    Privilege escalation in the Shell Integration component

    Privilege escalation in the Shell Integration component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • High 8.8
    CVE-2026-74969

    Race condition, use-after-free in the Layout: Text and Fonts component

    Race condition, use-after-free in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.1
    CVE-2026-74957

    Mitigation bypass in the Safe Browsing component

    Mitigation bypass in the Safe Browsing component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.1
    CVE-2026-74960

    Site isolation issue in the WebExtensions component

    Site isolation issue in the WebExtensions component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.1
    CVE-2026-74962

    Site isolation issue in the Networking: Cookies component

    Site isolation issue in the Networking: Cookies component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.1
    CVE-2026-74983

    Mitigation bypass in the Data Loss Prevention component

    Mitigation bypass in the Data Loss Prevention component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 7.5
    CVE-2026-74934

    Site isolation issue in the Graphics: CanvasWebGL component

    Site isolation issue in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Medium 6.5
    CVE-2026-74945 Public exploit

    Information disclosure in the Graphics: Text component

    Information disclosure in the Graphics: Text component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Medium 6.5
    CVE-2026-74948

    Information disclosure in the Graphics component

    Information disclosure in the Graphics component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Medium 6.5
    CVE-2026-74976

    JIT miscompilation in the JavaScript Engine: JIT component

    JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Medium 5.4
    CVE-2026-74963

    Same-origin policy bypass in the Networking: Cookies component

    Same-origin policy bypass in the Networking: Cookies component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Medium 5.4
    CVE-2026-74967

    Same-origin policy bypass in the Audio/Video: Playback component

    Same-origin policy bypass in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Medium 5.4
    CVE-2026-74974

    Same-origin policy bypass in the Graphics: ImageLib component

    Same-origin policy bypass in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Medium 4.3
    CVE-2026-74971

    Information disclosure in the DOM: UI Events & Focus Handling component

    Information disclosure in the DOM: UI Events & Focus Handling component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Medium 4.3
    CVE-2026-74972

    Information disclosure in the DOM: Push Subscriptions component

    Information disclosure in the DOM: Push Subscriptions component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Medium 4.2
    CVE-2026-74973

    Race condition, use-after-free in the Graphics component

    Race condition, use-after-free in the Graphics component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu

References

  • article
    https://access.redhat.com/security/updates/classification/#important
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517819
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517820
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517822
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517823
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517825
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517826
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517831
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517833
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517834
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517835
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517836
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517837
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517839
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517840
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517841
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517845
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517846
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517849
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517851
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517853
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517856
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517858
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517859
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517860
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517862
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517863
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517866
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517868
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517870
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517872
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517874
  • advisory
    https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_65110.json
  • report
    https://access.redhat.com/security/cve/CVE-2026-74934
  • advisory
    https://www.cve.org/CVERecord?id=CVE-2026-74934
  • advisory
    https://nvd.nist.gov/vuln/detail/CVE-2026-74934
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-76/#CVE-2026-74934
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-79/#CVE-2026-74934
  • report
    https://access.redhat.com/security/cve/CVE-2026-74935