CVE-2026-84121

EUVD-2026-69066
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
mozillaCNA
9.6 CRITICAL
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 23.28%
Affected Products (NVD)
VendorProductVersion
mozillafirefox
𝑥
< 115.40.0
mozillafirefox
116.0 ≤
𝑥
< 140.15.0
mozillafirefox
141.0.0 ≤
𝑥
< 153.2.0
mozillathunderbird
𝑥
< 140.15.0
mozillathunderbird
141.0 ≤
𝑥
< 153.2.0
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
mozillafirefox
154.0.0 ≤
𝑥
< 155.0.0
CNA
mozillafirefox_esr
𝑥
< 115.40.0
CNA
mozillafirefox_esr
116.0 ≤
𝑥
< 140.15.0
CNA
mozillafirefox_esr
141.0.0 ≤
𝑥
< 153.2.0
CNA
mozillathunderbird
154.0 ≤
𝑥
< 155.0
CNA
mozillathunderbird_esr
𝑥
< 140.15.0
CNA
mozillathunderbird_esr
141.0 ≤
𝑥
< 153.2.0
CNA
Debian logo
Debian Releases
Debian Product
Codename
firefox
sid
157.0.1-1
fixed
firefox-esr
bookworm
vulnerable
bookworm (security)
153.4.0esr-1~deb12u1
fixed
forky
153.4.0esr-1
fixed
sid
153.4.0esr-1
fixed
trixie
140.15.0esr-1~deb13u1
fixed
trixie (security)
153.4.0esr-1~deb13u1
fixed
thunderbird
bookworm
vulnerable
bookworm (security)
1:140.17.0esr-1~deb12u1
fixed
forky
1:153.4.0esr-1
fixed
sid
1:153.4.0esr-1
fixed
trixie
vulnerable
trixie (security)
1:140.17.0esr-1~deb13u1
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
firefox
jammy
not-affected
noble
not-affected
resolute
not-affected
thunderbird
jammy
needed
noble
not-affected
resolute
not-affected
mozjs38
bionic
needs-triage
jammy
dne
noble
dne
resolute
dne
mozjs52
bionic
ignored
focal
ignored
jammy
dne
noble
dne
resolute
dne
mozjs68
focal
ignored
jammy
dne
noble
dne
resolute
dne
mozjs78
jammy
ignored
noble
dne
resolute
dne
mozjs91
jammy
ignored
noble
dne
resolute
dne
mozjs102
jammy
ignored
noble
ignored
resolute
dne
mozjs115
jammy
dne
noble
ignored
resolute
dne
openSUSE logo
openSUSE / SLES Releases
openSUSE Product
Release
MozillaFirefox
suse enterprise desktop 15 SP7
153.2.0-150400.157.5.1
fixed
suse enterprise sap 12 SP5
153.2.0-118.5.4
fixed
suse enterprise sap 15 SP4
153.2.0-150400.157.5.1
fixed
suse enterprise sap 15 SP5
153.2.0-150400.157.5.1
fixed
suse enterprise sap 15 SP6
153.2.0-150400.157.5.1
fixed
suse enterprise sap 15 SP7
153.2.0-150400.157.5.1
fixed
suse enterprise server 12 SP5
153.2.0-118.5.4
fixed
suse enterprise server 15 SP4
153.2.0-150400.157.5.1
fixed
suse enterprise server 15 SP5
153.2.0-150400.157.5.1
fixed
suse enterprise server 15 SP6
153.2.0-150400.157.5.1
fixed
suse enterprise server 15 SP7
153.2.0-150400.157.5.1
fixed
MozillaFirefox-branding-SLE-153
suse enterprise desktop 15 SP7
150400.14.3.1
fixed
suse enterprise sap 12 SP5
41.3.8
fixed
suse enterprise sap 15 SP4
150400.14.3.1
fixed
suse enterprise sap 15 SP5
150400.14.3.1
fixed
suse enterprise sap 15 SP6
150400.14.3.1
fixed
suse enterprise sap 15 SP7
150400.14.3.1
fixed
suse enterprise server 12 SP5
41.3.8
fixed
suse enterprise server 15 SP4
150400.14.3.1
fixed
suse enterprise server 15 SP5
150400.14.3.1
fixed
suse enterprise server 15 SP6
150400.14.3.1
fixed
suse enterprise server 15 SP7
150400.14.3.1
fixed
MozillaFirefox-devel
suse enterprise desktop 15 SP7
153.2.0-150400.157.5.1
fixed
suse enterprise sap 12 SP5
153.2.0-118.5.4
fixed
suse enterprise sap 15 SP4
153.2.0-150400.157.5.1
fixed
suse enterprise sap 15 SP5
153.2.0-150400.157.5.1
fixed
suse enterprise sap 15 SP6
153.2.0-150400.157.5.1
fixed
suse enterprise sap 15 SP7
153.2.0-150400.157.5.1
fixed
suse enterprise server 12 SP5
153.2.0-118.5.4
fixed
suse enterprise server 15 SP4
153.2.0-150400.157.5.1
fixed
suse enterprise server 15 SP5
153.2.0-150400.157.5.1
fixed
suse enterprise server 15 SP6
153.2.0-150400.157.5.1
fixed
suse enterprise server 15 SP7
153.2.0-150400.157.5.1
fixed
MozillaFirefox-translations-common
suse enterprise desktop 15 SP7
153.2.0-150400.157.5.1
fixed
suse enterprise sap 12 SP5
153.2.0-118.5.4
fixed
suse enterprise sap 15 SP4
153.2.0-150400.157.5.1
fixed
suse enterprise sap 15 SP5
153.2.0-150400.157.5.1
fixed
suse enterprise sap 15 SP6
153.2.0-150400.157.5.1
fixed
suse enterprise sap 15 SP7
153.2.0-150400.157.5.1
fixed
suse enterprise server 12 SP5
153.2.0-118.5.4
fixed
suse enterprise server 15 SP4
153.2.0-150400.157.5.1
fixed
suse enterprise server 15 SP5
153.2.0-150400.157.5.1
fixed
suse enterprise server 15 SP6
153.2.0-150400.157.5.1
fixed
suse enterprise server 15 SP7
153.2.0-150400.157.5.1
fixed
MozillaFirefox-translations-other
suse enterprise desktop 15 SP7
153.2.0-150400.157.5.1
fixed
suse enterprise sap 15 SP4
153.2.0-150400.157.5.1
fixed
suse enterprise sap 15 SP5
153.2.0-150400.157.5.1
fixed
suse enterprise sap 15 SP6
153.2.0-150400.157.5.1
fixed
suse enterprise sap 15 SP7
153.2.0-150400.157.5.1
fixed
suse enterprise server 15 SP4
153.2.0-150400.157.5.1
fixed
suse enterprise server 15 SP5
153.2.0-150400.157.5.1
fixed
suse enterprise server 15 SP6
153.2.0-150400.157.5.1
fixed
suse enterprise server 15 SP7
153.2.0-150400.157.5.1
fixed
Red Hat logo
Red Hat Enterprise Linux Releases
Red Hat Product
Release
firefox
RHEL 9
0:140.15.0-1.el9_8
fixed
firefox-x11
RHEL 9
0:140.15.0-1.el9_8
fixed
thunderbird
RHEL 9
0:140.16.0-1.el9_8
fixed
Amazon Linux logo
Amazon Linux Releases
Amazon Package
Release
firefox
Amazon Linux 2023
0:140.16.0-1.amzn2023.0.1
fixed
firefox-debuginfo
Amazon Linux 2023
0:140.16.0-1.amzn2023.0.1
fixed
firefox-debugsource
Amazon Linux 2023
0:140.16.0-1.amzn2023.0.1
fixed
Common Weakness Enumeration
References
https://bugzilla.mozilla.org/show_bug.cgi?id=2059018
https://www.mozilla.org/security/advisories/mfsa2026-82/
https://www.mozilla.org/security/advisories/mfsa2026-83/
https://www.mozilla.org/security/advisories/mfsa2026-84/
https://www.mozilla.org/security/advisories/mfsa2026-85/
https://www.mozilla.org/security/advisories/mfsa2026-86/
https://www.mozilla.org/security/advisories/mfsa2026-87/
https://www.mozilla.org/security/advisories/mfsa2026-88/