high 8.8

CVE-2026-92021 json

Use-after-free in the JavaScript Engine: JIT component

published 2026-09-15 55 d ago modified 2026-10-06 34 d ago also EUVD-2026-78484

cvss: 8.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 20%
public exploits: 0; none known

Use-after-free in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox ESR 140.16 and Thunderbird 140.16.

Patch / fix

fixed in 4 distros 5

mozilla firefox 140.16
mozilla firefox_esr 140.16
mozilla thunderbird 140.16
mozilla thunderbird_esr 140.16

debian red hat opensuse almalinux rocky linux

firefox-esr Debian 12 140.16.0esr-1~deb12u1
firefox-esr Debian 13 140.16.0esr-1~deb13u1
firefox-esr Debian 14 140.16.0esr-1
thunderbird Debian 12 1:140.16.0esr-1~deb12u1
thunderbird Debian 13 1:140.16.0esr-1~deb13u1
thunderbird Debian 14 1:153.3.0esr-1

debian advisories DEBIAN-CVE-2026-92021

thunderbird RHEL 8 140.16.0-1.el8_10
thunderbird RHEL 10.2 140.16.0-1.el10_2
firefox RHEL 8 140.16.0-1.el8_10
thunderbird RHEL 9 140.16.0-1.el9_8
firefox RHEL 9 140.16.0-1.el9_8
firefox-x11 RHEL 9 140.16.0-1.el9_8
firefox RHEL 10.2 140.16.0-1.el10_2
firefox RHEL 7 ELS 140.16.0-1.el7_9

red hat advisories RHSA-2026:83496 RHSA-2026:83077 RHSA-2026:83076 RHSA-2026:82818 RHSA-2026:82817 RHSA-2026:82779

MozillaThunderbird openSUSE Tumbleweed 140.16.0-1.1

opensuse advisories openSUSE-SU-2026:11827-1

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

almalinux advisories ALSA-2026:73971 ALSA-2026:73130 ALSA-2026:71652 ALSA-2026:70642 ALSA-2026:69461 ALSA-2026:69462

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

rocky linux advisories RLSA-2026:73971 RLSA-2026:73130 RLSA-2026:71652 RLSA-2026:70642 RLSA-2026:69462 RLSA-2026:69461

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-2026-92021 updated 2026-11-05 cvss 7.5

firefox: thunderbird: Use-after-free in the JavaScript Engine: JIT component

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 140.16.0-1.el8_10, thunderbird 140.16.0-1.el8_10
fixed: vendor fix RHSA-2026:71652
Red Hat Enterprise Linux AppStream (v. 9) firefox 140.16.0-1.el9_8, firefox-x11 140.16.0-1.el9_8, thunderbird 140.16.0-1.el9_8
fixed: vendor fix RHSA-2026:69462
Red Hat Enterprise Linux AppStream (v. 10) firefox 140.16.0-1.el10_2, thunderbird 140.16.0-1.el10_2
fixed: vendor fix RHSA-2026:69461
Red Hat Enterprise Linux AppStream AUS (v.8.4) firefox 140.16.0-1.el8_4, thunderbird 140.16.0-1.el8_4
fixed: vendor fix RHSA-2026:82779
Red Hat Enterprise Linux AppStream AUS (v.8.6) firefox 140.16.0-1.el8_6, thunderbird 140.16.0-1.el8_6
fixed: vendor fix RHSA-2026:83076
Red Hat Enterprise Linux AppStream E4S (v.8.8) firefox 140.16.0-1.el8_8, thunderbird 140.16.0-1.el8_8
fixed: vendor fix RHSA-2026:82720

show 8 more

Red Hat Enterprise Linux AppStream E4S (v.9.2) firefox 140.16.0-1.el9_2, firefox-x11 140.16.0-1.el9_2, thunderbird 140.16.0-1.el9_2
fixed: vendor fix RHSA-2026:82780
Red Hat Enterprise Linux AppStream E4S (v.9.4) firefox 140.16.0-1.el9_4, firefox-x11 140.16.0-1.el9_4, thunderbird 140.16.0-1.el9_4
fixed: vendor fix RHSA-2026:83077
Red Hat Enterprise Linux AppStream EUS (v. 10.0) firefox 140.16.0-1.el10_0, thunderbird 140.16.0-1.el10_0
fixed: vendor fix RHSA-2026:82818
Red Hat Enterprise Linux AppStream EUS (v.9.6) firefox 140.16.0-1.el9_6, firefox-x11 140.16.0-1.el9_6, thunderbird 140.16.0-1.el9_6
fixed: vendor fix RHSA-2026:82817
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) firefox 140.16.0-1.el8_4, thunderbird 140.16.0-1.el8_4
fixed: vendor fix RHSA-2026:82779
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) firefox 140.16.0-1.el8_6, thunderbird 140.16.0-1.el8_6
fixed: vendor fix RHSA-2026:83076
Red Hat Enterprise Linux AppStream TUS (v.8.8) firefox 140.16.0-1.el8_8, thunderbird 140.16.0-1.el8_8
fixed: vendor fix RHSA-2026:82720
Red Hat Enterprise Linux Server (v. 7 ELS) firefox 140.16.0-1.el7_9
fixed: vendor fix RHSA-2026:83496

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: 50 d ago (2026-09-20)

Exploit prediction

0.28% chance of exploitation in the next 30 days, higher than 20% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

Mozilla Firefox
Mozilla Thunderbird

Classification

Weakness

CWE-416 Use After Free

References

mozilla.org /security/advisories/mfsa2026-92/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-95/
vendor-advisory
bugzilla.mozilla.org /show_bug.cgi?id=2067208
permissions-required

Sources

CVE List CVE-2026-92021
NVD CVE-2026-92021

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