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OpenAdvisories
Critical RHSA-2026:80503 13 CVEs

Red Hat Security Advisory: thunderbird security update

Published Oct 14, 2026 · Updated Oct 14, 2026

Ecosystem: Red Hat

Fixed packages 3

ReleasePackageFixed in
Red Hat · RHEL 9.6 EUS rhel_eus:9.6::appstream thunderbird 0:140.15.0-1.el9_6
Red Hat · RHEL 9.6 EUS rhel_eus:9.6::appstream thunderbird-debuginfo 0:140.15.0-1.el9_6
Red Hat · RHEL 9.6 EUS rhel_eus:9.6::appstream thunderbird-debugsource 0:140.15.0-1.el9_6

Vulnerabilities 13

  • Critical 10.0
    CVE-2026-75874

    Sandbox escape in the Remote Settings Client component

    Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154, Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Critical 9.8
    CVE-2026-84143

    Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15

    Internally found bugs present in Thunderbird 154, Thunderbird ESR 153.1 and Thunderbird ESR 140.14. 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 bee…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Critical 9.6
    CVE-2026-84119

    Sandbox escape due to use-after-free in the DOM: Navigation component

    Sandbox escape due to use-after-free in the DOM: Navigation component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Critical 9.6
    CVE-2026-84121

    Sandbox escape due to use-after-free in the DOM: Security component

    Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Critical 9.1
    CVE-2026-84639

    Uninitialized memory in MIME parsing

    Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Thunderbird thunderbird thunderbird Debian Ubuntu
  • High 8.8
    CVE-2026-16365

    Privilege escalation in the DOM: Workers component

    Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 153, Thunderbird 153, Firefox ESR 140.15, and Thunderbird 140.15.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • High 8.8
    CVE-2026-84131

    Privilege escalation due to invalid pointer in the Graphics component

    Privilege escalation due to invalid pointer in the Graphics component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • High 7.5
    CVE-2026-84145

    Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15

    Internally found bugs present in Thunderbird 154, Thunderbird ESR 153.1 and Thunderbird ESR 140.14. 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 bee…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • High 7.5
    CVE-2026-84640

    One byte overflow read in mail parser

    A maliciously constructed mail header could lead to a one byte read past the end of a buffer. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Thunderbird thunderbird thunderbird Debian Ubuntu
  • High 7.5
    CVE-2026-84641

    Information disclosure due to malicious IMAP server response

    A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID response. Heap contents can ultimately be persisted to prefs.js. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Thunderbird thunderbird thunderbird Debian Ubuntu
  • Medium 5.4
    CVE-2026-84120

    Use-after-free in the Audio/Video component

    Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Medium 5.4
    CVE-2026-84122

    Use-after-free in the Audio/Video component

    Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Medium 5.4
    CVE-2026-84124

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

    Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

References

  • article
    https://access.redhat.com/security/updates/classification/#important
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2503504
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517832
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526753
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526760
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526764
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526765
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526767
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526773
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526778
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526781
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2527113
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2527115
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2527116
  • advisory
    https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_80503.json
  • report
    https://access.redhat.com/security/cve/CVE-2026-16365
  • advisory
    https://www.cve.org/CVERecord?id=CVE-2026-16365
  • advisory
    https://nvd.nist.gov/vuln/detail/CVE-2026-16365
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-68/#CVE-2026-16365
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-71/#CVE-2026-16365
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-84/#CVE-2026-16365
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-87/#CVE-2026-16365
  • report
    https://access.redhat.com/security/cve/CVE-2026-75874
  • advisory
    https://www.cve.org/CVERecord?id=CVE-2026-75874
  • advisory
    https://nvd.nist.gov/vuln/detail/CVE-2026-75874
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-74/#CVE-2026-75874
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-78/#CVE-2026-75874
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-84/#CVE-2026-75874
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-87/#CVE-2026-75874
  • report
    https://access.redhat.com/security/cve/CVE-2026-84119
  • advisory
    https://www.cve.org/CVERecord?id=CVE-2026-84119
  • advisory
    https://nvd.nist.gov/vuln/detail/CVE-2026-84119
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-84/#CVE-2026-84119
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-87/#CVE-2026-84119
  • report
    https://access.redhat.com/security/cve/CVE-2026-84120
  • advisory
    https://www.cve.org/CVERecord?id=CVE-2026-84120
  • advisory
    https://nvd.nist.gov/vuln/detail/CVE-2026-84120
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-84/#CVE-2026-84120
  • article
    https://www.mozilla.org/security/advisories/mfsa2026-87/#CVE-2026-84120