critical 9.6

CVE-2026-7321 json

Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component

published 2026-04-28 6 mo ago modified 2026-10-26 13 d ago also EUVD-2026-26058

cvss: 9.6; 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 17%
public exploits: 0; none known

Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component. This vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, and Thunderbird 140.10.1.

Patch / fix

fixed in 4 distros 5

mozilla firefox 140.10.1, 150
mozilla firefox_esr 140.10.1, 150
mozilla thunderbird 150
mozilla thunderbird_esr 150

debian red hat opensuse almalinux rocky linux

firefox-esr Debian 12 140.10.1esr-1~deb12u1
firefox-esr Debian 13 140.10.1esr-1~deb13u1
firefox-esr Debian 14 140.10.1esr-1
thunderbird Debian 12 1:140.10.1esr-1~deb12u1
thunderbird Debian 13 1:140.10.1esr-1~deb13u1
thunderbird Debian 14 1:140.10.1esr-1

debian advisories DEBIAN-CVE-2026-7321

thunderbird RHEL 8 140.10.1-1.el8_10
firefox RHEL 8 140.10.1-1.el8_10
firefox RHEL 9 140.10.1-1.el9_8
firefox-x11 RHEL 9 140.10.1-1.el9_8
thunderbird RHEL 9 140.10.1-1.el9_8
firefox RHEL 10.2 140.10.1-1.el10_2
thunderbird RHEL 10.2 140.10.1-1.el10_2
thunderbird RHEL 8.6 EUS_LONG_LIFE, RHEL 8.6 AUS 140.10.1-1.el8_6

red hat advisories RHSA-2026:25014 RHSA-2026:24844 RHSA-2026:24846 RHSA-2026:24719 RHSA-2026:24721 RHSA-2026:24717

MozillaThunderbird openSUSE Leap 16.0 140.12.0-bp160.1.1
MozillaThunderbird openSUSE Tumbleweed 140.10.1-1.1
firefox-esr openSUSE Tumbleweed 140.10.1-1.1

opensuse advisories openSUSE-SU-2026:21168-1 openSUSE-SU-2026:10687-1 openSUSE-SU-2026:10661-1

thunderbird AlmaLinux 8 140.10.1-1.el8_10.alma.1
firefox AlmaLinux 8 140.10.1-1.el8_10.alma.1
thunderbird AlmaLinux 10 140.10.1-1.el10_2.alma.1
firefox AlmaLinux 10 140.10.1-1.el10_2
thunderbird AlmaLinux 9 140.10.1-1.el9_8.alma.1
firefox AlmaLinux 9 140.10.1-1.el9_8.alma.1
firefox-x11 AlmaLinux 9 140.10.1-1.el9_8.alma.1

almalinux advisories ALSA-2026:20586 ALSA-2026:19588 ALSA-2026:19153 ALSA-2026:19157 ALSA-2026:19348 ALSA-2026:19370

thunderbird Rocky Linux 10 140.10.1-1.el10_2
thunderbird Rocky Linux 8 140.10.1-1.el8_10
thunderbird Rocky Linux 9 140.10.1-1.el9_8
firefox Rocky Linux 9 140.10.1-1.el9_8
firefox Rocky Linux 8 140.10.1-1.el8_10

rocky linux advisories RLSA-2026:19153 RLSA-2026:20586 RLSA-2026:19348 RLSA-2026:19370 RLSA-2026:19588

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-2026-7321 updated 2026-11-05 cvss 6.1

firefox: thunderbird: webrtc: Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking 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 140.10.1-1.el8_10, thunderbird 140.10.1-1.el8_10
fixed: vendor fix RHSA-2026:19588
Red Hat Enterprise Linux AppStream (v. 9) firefox 140.10.1-1.el9_8, firefox-x11 140.10.1-1.el9_8, thunderbird 140.10.1-1.el9_8
fixed: vendor fix RHSA-2026:19370
Red Hat Enterprise Linux AppStream (v. 10) firefox 140.10.1-1.el10_2, thunderbird 140.10.1-1.el10_2
fixed: vendor fix RHSA-2026:19157
Red Hat Enterprise Linux AppStream AUS (v.8.4) firefox 140.10.1-1.el8_4, thunderbird 140.10.1-1.el8_4
fixed: vendor fix RHSA-2026:22712
Red Hat Enterprise Linux AppStream AUS (v.8.6) firefox 140.10.1-1.el8_6, thunderbird 140.10.1-1.el8_6
fixed: vendor fix RHSA-2026:24345
Red Hat Enterprise Linux AppStream E4S (v.8.8) firefox 140.10.1-1.el8_8, thunderbird 140.10.1-1.el8_8
fixed: vendor fix RHSA-2026:22847

show 9 more

Red Hat Enterprise Linux AppStream E4S (v.9.0) firefox 140.10.1-1.el9_0
fixed: vendor fix RHSA-2026:21743
Red Hat Enterprise Linux AppStream E4S (v.9.2) firefox 140.10.1-1.el9_2, firefox-x11 140.10.1-1.el9_2, thunderbird 140.10.1-1.el9_2
fixed: vendor fix RHSA-2026:22410
Red Hat Enterprise Linux AppStream E4S (v.9.4) firefox 140.10.1-1.el9_4, firefox-x11 140.10.1-1.el9_4, thunderbird 140.10.1-1.el9_4
fixed: vendor fix RHSA-2026:22324
Red Hat Enterprise Linux AppStream EUS (v. 10.0) firefox 140.10.1-1.el10_0, thunderbird 140.10.1-1.el10_0
fixed: vendor fix RHSA-2026:22408
Red Hat Enterprise Linux AppStream EUS (v.9.6) firefox 140.10.1-1.el9_6, firefox-x11 140.10.1-1.el9_6, thunderbird 140.10.1-1.el9_6
fixed: vendor fix RHSA-2026:22409
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) firefox 140.10.1-1.el8_4, thunderbird 140.10.1-1.el8_4
fixed: vendor fix RHSA-2026:22712
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) firefox 140.10.1-1.el8_6, thunderbird 140.10.1-1.el8_6
fixed: vendor fix RHSA-2026:24345
Red Hat Enterprise Linux AppStream TUS (v.8.8) firefox 140.10.1-1.el8_8, thunderbird 140.10.1-1.el8_8
fixed: vendor fix RHSA-2026:22847
Red Hat Enterprise Linux Server (v. 7 ELS) firefox 140.10.1-1.el7_9
fixed: vendor fix RHSA-2026:22708

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: 6 mo ago (2026-04-28)

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	9.6	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
CNA	3.1	9.6	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Affected products

Mozilla Firefox
Mozilla Thunderbird

Classification

Weakness

CWE-120 Buffer Copy without Checking Size of Input

References

mozilla.org /security/advisories/mfsa2026-30/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-33/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-36/
vendor-advisory
mozilla.org /security/advisories/mfsa2026-39/
vendor-advisory
bugzilla.mozilla.org /show_bug.cgi?id=2029461
permissions-required

Sources

CVE List CVE-2026-7321
NVD CVE-2026-7321

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