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High RLSA-2026:67129 10 CVEs

Important: firefox security update

Published Sep 27, 2026 · Updated Sep 27, 2026

Ecosystem: Rocky Linux

Summary

Mozilla Firefox is an open-source web browser, designed for standards compliance, performance, and portability.

Security Fix(es):

* firefox: thunderbird: Privilege escalation in the DOM: Workers component (CVE-2026-16365)

* firefox: thunderbird: Sandbox escape in the Remote Settings Client component (CVE-2026-75874)

* firefox: Sandbox escape due to use-after-free in the DOM: Security component (CVE-2026-84121)

* firefox: Internally found bugs fixed in Firefox 155, Firefox ESR 153.2, Firefox ESR 140.15 and Firefox ESR 115.40 (CVE-2026-84145)

* firefox: Sandbox escape due to use-after-free in the DOM: Navigation component (CVE-2026-84119)

* firefox: Use-after-free in the Audio/Video component (CVE-2026-84120)

* firefox: Privilege escalation due to invalid pointer in the Graphics component (CVE-2026-84131)

* firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-84124)

* firefox: Use-after-free in the Audio/Video component (CVE-2026-84122)

* firefox: Internally found bugs fixed in Firefox 155, Firefox ESR 153.2 and Firefox ESR 140.15 (CVE-2026-84143)

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.

Fixed packages 1

ReleasePackageFixed in
Rocky Linux · 10 firefox 0:140.15.0-1.el10_2

Vulnerabilities 10

  • 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
  • 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
  • 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

  • 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
  • advisory
    https://access.redhat.com/errata/RHSA-2026:67129