high 7.5

CVE-2026-84145 json

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

published 2026-09-01 2 mo ago modified 2026-09-03 2 mo ago also EUVD-2026-69068

cvss: 7.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits: 0; none known

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 been exploited. 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.

Patch / fix

fixed in 2 distros 6

mozilla firefox 115.40.0, 140.15.0, 153.2.0, 155.0.0
mozilla thunderbird 140.15.0, 153.2.0, 155.0

debian red hat suse opensuse almalinux rocky linux

firefox-esr Debian 12 140.15.0esr-1~deb12u1
firefox-esr Debian 13 140.15.0esr-1~deb13u1
firefox-esr Debian 14 140.15.0esr-1
thunderbird Debian 12 1:140.15.0esr-1~deb12u1
thunderbird Debian 13 1:140.15.0esr-1~deb13u1
thunderbird Debian 14 1:153.2.0esr-1

debian advisories DEBIAN-CVE-2026-84145

thunderbird RHEL 8 140.16.0-1.el8_10
thunderbird RHEL 10.2 140.16.0-1.el10_2
firefox RHEL 8 140.15.0-1.el8_10
firefox RHEL 9 140.15.0-1.el9_8
firefox-x11 RHEL 9 140.15.0-1.el9_8
firefox RHEL 10.2 140.15.0-1.el10_2
thunderbird RHEL 9 140.16.0-1.el9_8
thunderbird RHEL 8.4 EUS_LONG_LIFE, RHEL 8.4 AUS 140.16.0-1.el8_4

red hat advisories RHSA-2026:82122 RHSA-2026:81913 RHSA-2026:81912 RHSA-2026:80503 RHSA-2026:77632 RHSA-2026:77631

MozillaThunderbird SLE Workstation Extension 15 SP7, SLE Module for Package Hub 15 SP7 153.2.0-150400.13.3.1
MozillaFirefox SLES for SAP applications 16.0, SLES 16.0 153.2.0-160000.1.1
mozilla-nss SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +11 more 3.125-150400.3.74.1
mozilla-nspr SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +11 more 4.39-150400.12.3.1
MozillaFirefox SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 153.2.0-150400.157.5.1
MozillaFirefox-branding-SLE SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 153-150400.14.3.1
mozilla-nss SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 3.125-58.147.1
mozilla-nspr SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 4.39-19.39.1

suse advisories SUSE-SU-2026:4268-1 SUSE-SU-2026:23784-1 SUSE-SU-2026:4156-1 SUSE-SU-2026:4140-1

MozillaFirefox openSUSE Leap 16.0 153.2.0-160000.1.1
MozillaFirefox openSUSE Tumbleweed 155.0-1.1
MozillaThunderbird openSUSE Tumbleweed 140.15.0-1.1
firefox-esr openSUSE Tumbleweed 153.2.0-1.1

opensuse advisories openSUSE-SU-2026:21853-1 openSUSE-SU-2026:11677-1 openSUSE-SU-2026:11678-1 openSUSE-SU-2026:11666-1

thunderbird AlmaLinux 8 140.16.0-1.el8_10.alma.1
thunderbird AlmaLinux 10 140.16.0-1.el10_2.alma.1
thunderbird AlmaLinux 9 140.16.0-1.el9_8.alma.1
firefox AlmaLinux 8 140.15.0-1.el8_10.alma.1
firefox AlmaLinux 10 140.15.0-1.el10_2
firefox AlmaLinux 9 140.15.0-1.el9_8.alma.1
firefox-x11 AlmaLinux 9 140.15.0-1.el9_8.alma.1

almalinux advisories ALSA-2026:73971 ALSA-2026:73130 ALSA-2026:70642 ALSA-2026:68549 ALSA-2026:67129 ALSA-2026:67133

thunderbird Rocky Linux 8 140.16.0-1.el8_10
thunderbird Rocky Linux 10 140.16.0-1.el10_2
firefox Rocky Linux 10 140.15.0-1.el10_2
firefox Rocky Linux 9 140.15.0-1.el9_8
firefox Rocky Linux 8 140.15.0-1.el8_10
thunderbird Rocky Linux 9 140.16.0-1.el9_8

rocky linux advisories RLSA-2026:73971 RLSA-2026:73130 RLSA-2026:67129 RLSA-2026:67133 RLSA-2026:68549 RLSA-2026:70642

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-84145 updated 2026-11-04 cvss 7.5

firefox: Internally found bugs fixed in Firefox 155, Firefox ESR 153.2, Firefox ESR 140.15 and Firefox ESR 115.40

Red Hat Enterprise Linux 6 firefox, thunderbird Red Hat Enterprise Linux 7 thunderbird
affected: no fix planned “Out of support scope”
Red Hat Enterprise Linux 10 rhel10/firefox-flatpak, rhel10/thunderbird-flatpak
affected: no fix available
Red Hat Enterprise Linux AppStream (v. 8) firefox 140.15.0-1.el8_10, thunderbird 140.16.0-1.el8_10
fixed: vendor fix RHSA-2026:68549
Red Hat Enterprise Linux AppStream (v. 9) firefox 140.15.0-1.el9_8, firefox-x11 140.15.0-1.el9_8, thunderbird 140.16.0-1.el9_8
fixed: vendor fix RHSA-2026:67133
Red Hat Enterprise Linux AppStream (v. 10) firefox 140.15.0-1.el10_2, thunderbird 140.16.0-1.el10_2
fixed: vendor fix RHSA-2026:67129
Red Hat Enterprise Linux AppStream AUS (v.8.4) firefox 140.15.0-1.el8_4, thunderbird 140.16.0-1.el8_4
fixed: vendor fix RHSA-2026:76894
Red Hat Enterprise Linux AppStream AUS (v.8.6) firefox 140.15.0-1.el8_6, thunderbird 140.16.0-1.el8_6
fixed: vendor fix RHSA-2026:76745
Red Hat Enterprise Linux AppStream E4S (v.8.8) firefox 140.15.0-1.el8_8, thunderbird 140.16.0-1.el8_8
fixed: vendor fix RHSA-2026:76746

show 8 more

Red Hat Enterprise Linux AppStream E4S (v.9.2) firefox 140.15.0-1.el9_2, firefox-x11 140.15.0-1.el9_2, thunderbird 140.15.0-1.el9_2
fixed: vendor fix RHSA-2026:76742
Red Hat Enterprise Linux AppStream E4S (v.9.4) firefox 140.15.0-1.el9_4, firefox-x11 140.15.0-1.el9_4, thunderbird 140.15.0-1.el9_4
fixed: vendor fix RHSA-2026:76740
Red Hat Enterprise Linux AppStream EUS (v. 10.0) firefox 140.15.0-1.el10_0, thunderbird 140.15.0-1.el10_0
fixed: vendor fix RHSA-2026:77610
Red Hat Enterprise Linux AppStream EUS (v.9.6) firefox 140.15.0-1.el9_6, firefox-x11 140.15.0-1.el9_6, thunderbird 140.15.0-1.el9_6
fixed: vendor fix RHSA-2026:76895
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) firefox 140.15.0-1.el8_4, thunderbird 140.16.0-1.el8_4
fixed: vendor fix RHSA-2026:76894
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) firefox 140.15.0-1.el8_6, thunderbird 140.16.0-1.el8_6
fixed: vendor fix RHSA-2026:76745
Red Hat Enterprise Linux AppStream TUS (v.8.8) firefox 140.15.0-1.el8_8, thunderbird 140.16.0-1.el8_8
fixed: vendor fix RHSA-2026:76746
Red Hat Enterprise Linux Server (v. 7 ELS) firefox 140.15.0-1.el7_9
fixed: vendor fix RHSA-2026:76741

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 2 mo ago (2026-09-01)

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	7.5	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA	3.1	7.5	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

Mozilla Firefox
Mozilla Thunderbird

Classification

Weakness

CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

References

mozilla.org /security/advisories/mfsa2026-82/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-83/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-84/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-85/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-86/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-87/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-88/
vendor-advisory
bugzilla.mozilla.org /buglist.cgi?bug_id=2054640%2C2054650%2C2054652%2C2055693%2C2055705%2C2058051%2C2058652%2C2058660%2C2059027%2C
broken-link
bugzilla.mozilla.org /buglist.cgi?bug_id=2058001%2C2059139%2C2062400%2C2062419
broken-link
bugzilla.mozilla.org /show_bug.cgi?id=2055678
permissions-required

Sources

CVE List CVE-2026-84145
NVD CVE-2026-84145

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary