high 8.1

CVE-2026-12327 json

Memory safety bugs fixed in Firefox ESR 140.12, Thunderbird ESR 140.12, Firefox 152 and Thunderbird 152

published 2026-06-16 4 mo ago modified 2026-10-26 14 d ago also EUVD-2026-37073

cvss: 8.1; 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 35%
public exploits: 0; none known

Memory safety bugs present in Firefox ESR 140.11, Thunderbird ESR 140.11, Firefox 151 and Thunderbird 151. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.

Patch / fix

fixed in 4 distros 6

mozilla firefox 140.12, 152
mozilla firefox_esr 140.12, 152
mozilla thunderbird 140.12, 152
mozilla thunderbird_esr 140.12, 152

debian red hat suse opensuse almalinux rocky linux

firefox-esr Debian 12 140.12.0esr-1~deb12u1
firefox-esr Debian 13 140.12.0esr-1~deb13u1
firefox-esr Debian 14 140.12.0esr-1
thunderbird Debian 12 1:140.12.0esr-1~deb12u1
thunderbird Debian 13 1:140.12.0esr-1~deb13u1
thunderbird Debian 14 1:140.12.0esr-1

debian advisories DEBIAN-CVE-2026-12327

thunderbird RHEL 8 140.12.0-1.el8_10
thunderbird RHEL 10.2 140.12.0-1.el10_2
thunderbird RHEL 9 140.12.0-1.el9_8
firefox RHEL 9 140.12.0-1.el9_8
firefox-x11 RHEL 9 140.12.0-1.el9_8
firefox RHEL 10.2 140.12.0-1.el10_2
firefox RHEL 8 140.12.0-1.el8_10
thunderbird RHEL 9.2 E4S 140.12.0-1.el9_2

red hat advisories RHSA-2026:39706 RHSA-2026:39428 RHSA-2026:39142 RHSA-2026:39141 RHSA-2026:39011 RHSA-2026:38751

MozillaFirefox SLES 16.0, SLES for SAP applications 16.0 140.13.0-160000.1.1
MozillaThunderbird SLE Workstation Extension 15 SP7, SLE Module for Package Hub 15 SP7 140.12.0-150200.8.277.1
MozillaFirefox SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 140.12.0-150200.152.245.1
MozillaFirefox SLES for SAP applications 16.0, SLES 16.0 140.12.0-160000.1.1
MozillaFirefox SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 140.12.0-112.321.1

suse advisories SUSE-SU-2026:23115-1 SUSE-SU-2026:23137-1 SUSE-SU-2026:2852-1 SUSE-SU-2026:2814-1 SUSE-SU-2026:22351-1 SUSE-SU-2026:2583-1

MozillaFirefox openSUSE Leap 16.0 140.13.0-160000.1.1
MozillaThunderbird openSUSE Leap 16.0 140.12.0-bp160.1.1
MozillaFirefox openSUSE Leap 16.0 140.12.0-160000.1.1
MozillaThunderbird openSUSE Tumbleweed 140.12.0-1.1
MozillaFirefox openSUSE Tumbleweed 152.0-1.1
firefox-esr openSUSE Tumbleweed 140.12.0-1.1

opensuse advisories openSUSE-SU-2026:21519-1 openSUSE-SU-2026:21168-1 openSUSE-SU-2026:21043-1 openSUSE-SU-2026:11072-1 openSUSE-SU-2026:11052-1 openSUSE-SU-2026:11055-1

thunderbird AlmaLinux 8 140.12.0-1.el8_10.alma.1
thunderbird AlmaLinux 10 140.12.0-1.el10_2.alma.1
thunderbird AlmaLinux 9 140.12.0-1.el9_8.alma.1
firefox AlmaLinux 8 140.12.0-1.el8_10.alma.1
firefox AlmaLinux 10 140.12.0-1.el10_2
firefox AlmaLinux 9 140.12.0-1.el9_8.alma.1
firefox-x11 AlmaLinux 9 140.12.0-1.el9_8.alma.1

almalinux advisories ALSA-2026:33445 ALSA-2026:30846 ALSA-2026:29940 ALSA-2026:27717 ALSA-2026:27733 ALSA-2026:27734

thunderbird Rocky Linux 10 140.12.0-1.el10_2
thunderbird Rocky Linux 8 140.12.0-1.el8_10
thunderbird Rocky Linux 9 140.12.0-1.el9_8
firefox Rocky Linux 8 140.12.0-1.el8_10
firefox Rocky Linux 10 140.12.0-1.el10_2
firefox Rocky Linux 9 140.12.0-1.el9_8

rocky linux advisories RLSA-2026:30846 RLSA-2026:33445 RLSA-2026:29940 RLSA-2026:27717 RLSA-2026:27733 RLSA-2026:27734

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-2026-12327 updated 2026-11-05 cvss 6.1

firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 140.12, Thunderbird ESR 140.12, Firefox 152 and Thunderbird 152

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 140.12.0-1.el8_10, thunderbird 140.12.0-1.el8_10
fixed: vendor fix RHSA-2026:27717
Red Hat Enterprise Linux AppStream (v. 9) firefox 140.12.0-1.el9_8, firefox-x11 140.12.0-1.el9_8, thunderbird 140.12.0-1.el9_8
fixed: vendor fix RHSA-2026:27734
Red Hat Enterprise Linux AppStream (v. 10) firefox 140.12.0-1.el10_2, thunderbird 140.12.0-1.el10_2
fixed: vendor fix RHSA-2026:27733
Red Hat Enterprise Linux AppStream AUS (v.8.4) firefox 140.12.0-1.el8_4, thunderbird 140.12.0-1.el8_4
fixed: vendor fix RHSA-2026:36102
Red Hat Enterprise Linux AppStream AUS (v.8.6) firefox 140.12.0-1.el8_6, thunderbird 140.12.0-1.el8_6
fixed: vendor fix RHSA-2026:37210
Red Hat Enterprise Linux AppStream E4S (v.8.8) firefox 140.12.0-1.el8_8, thunderbird 140.12.0-1.el8_8
fixed: vendor fix RHSA-2026:36103

show 8 more

Red Hat Enterprise Linux AppStream E4S (v.9.2) firefox 140.12.0-1.el9_2, firefox-x11 140.12.0-1.el9_2, thunderbird 140.12.0-1.el9_2
fixed: vendor fix RHSA-2026:36101
Red Hat Enterprise Linux AppStream E4S (v.9.4) firefox 140.12.0-1.el9_4, firefox-x11 140.12.0-1.el9_4, thunderbird 140.12.0-1.el9_4
fixed: vendor fix RHSA-2026:39011
Red Hat Enterprise Linux AppStream EUS (v. 10.0) firefox 140.12.0-1.el10_0, thunderbird 140.12.0-1.el10_0
fixed: vendor fix RHSA-2026:36100
Red Hat Enterprise Linux AppStream EUS (v.9.6) firefox 140.12.0-1.el9_6, firefox-x11 140.12.0-1.el9_6, thunderbird 140.12.0-1.el9_6
fixed: vendor fix RHSA-2026:37391
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) firefox 140.12.0-1.el8_4, thunderbird 140.12.0-1.el8_4
fixed: vendor fix RHSA-2026:36102
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) firefox 140.12.0-1.el8_6, thunderbird 140.12.0-1.el8_6
fixed: vendor fix RHSA-2026:37210
Red Hat Enterprise Linux AppStream TUS (v.8.8) firefox 140.12.0-1.el8_8, thunderbird 140.12.0-1.el8_8
fixed: vendor fix RHSA-2026:36103
Red Hat Enterprise Linux Server (v. 7 ELS) firefox 140.12.0-1.el7_9
fixed: vendor fix RHSA-2026:38506

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: 4 mo ago (2026-06-17)

Exploit prediction

0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	8.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA	3.1	8.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/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/mfsa2026-57/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-58/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-60/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-61/
vendor-advisory
bugzilla.mozilla.org /buglist.cgi?bug_id=2011842%2C2023902%2C2025512%2C2027312%2C2029444%2C2036571%2C2036900%2C2036936%2C2037995%2C
broken-link

Sources

CVE List CVE-2026-12327
NVD CVE-2026-12327

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary