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OpenAdvisories
Critical RHSA-2026:65633 21 CVEs

Red Hat Security Advisory: thunderbird security update

Published Sep 9, 2026 · Updated Sep 10, 2026

Ecosystem: Red Hat

Fixed packages 3

ReleasePackageFixed in
Red Hat · RHEL 10.0 EUS enterprise_linux_eus:10.0 thunderbird 0:140.14.0-1.el10_0
Red Hat · RHEL 10.0 EUS enterprise_linux_eus:10.0 thunderbird-debuginfo 0:140.14.0-1.el10_0
Red Hat · RHEL 10.0 EUS enterprise_linux_eus:10.0 thunderbird-debugsource 0:140.14.0-1.el10_0

Vulnerabilities 21

  • 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-2026-74964

    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-2026-74942

    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-2026-74953

    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 8.1
    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 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-2026-74974

    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=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=2517831
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517836
  • 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=2517845
  • 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=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=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_65633.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
  • advisory
    https://www.cve.org/CVERecord?id=CVE-2026-74935
  • advisory
    https://nvd.nist.gov/vuln/detail/CVE-2026-74935
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-76/#CVE-2026-74935
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-79/#CVE-2026-74935
  • report
    https://access.redhat.com/security/cve/CVE-2026-74936
  • advisory
    https://www.cve.org/CVERecord?id=CVE-2026-74936
  • advisory
    https://nvd.nist.gov/vuln/detail/CVE-2026-74936
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-76/#CVE-2026-74936
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-79/#CVE-2026-74936
  • report
    https://access.redhat.com/security/cve/CVE-2026-74939