medium 6.5

CVE-2025-9181 json

Uninitialized memory in the JavaScript Engine component

published 2025-08-19 last yr. modified 2026-10-05 last mo. also EUVD-2025-25244

cvss: 6.5; 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 35%
public exploits: 0; none known

Uninitialized memory in the JavaScript Engine component. This vulnerability was fixed in Firefox 142, Firefox ESR 128.14, Firefox ESR 140.2, Thunderbird 142, Thunderbird 128.14, and Thunderbird 140.2.

Patch / fix

fixed in 4 distros 7

mozilla firefox 128.14, 140.2, 142
mozilla firefox_esr 128.14, 140.2, 142
mozilla thunderbird 128.14, 140.2, 142
mozilla thunderbird_esr 128.14, 140.2, 142

debian ubuntu red hat suse opensuse almalinux rocky linux

firefox-esr Debian 12 128.14.0esr-1~deb12u1
firefox-esr Debian 13 128.14.0esr-1~deb13u1
firefox-esr Debian 14 128.14.0esr-1
thunderbird Debian 12 1:128.14.0esr-1~deb12u1
thunderbird Debian 13 1:128.14.0esr-1~deb13u1
thunderbird Debian 14 1:128.14.0esr-1

debian advisories DEBIAN-CVE-2025-9181

thunderbird Ubuntu 22.04 LTS 1:140.7.1+build1-0ubuntu0.22.04.1

ubuntu advisories UBUNTU-CVE-2025-9181

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

thunderbird RHEL 10.0 128.14.0-3.el10_0
thunderbird RHEL 8 128.14.0-3.el8_10
thunderbird RHEL 9 128.14.0-3.el9_6
firefox RHEL 8 128.14.0-2.el8_10
firefox RHEL 10.0 128.14.0-2.el10_0
firefox RHEL 9 128.14.0-2.el9_6
firefox-x11 RHEL 9 128.14.0-2.el9_6
thunderbird RHEL 8.6 TUS, RHEL 8.6 E4S, RHEL 8.6 AUS 128.14.0-3.el8_6

red hat advisories RHSA-2025:15535 RHSA-2025:15496 RHSA-2025:15438 RHSA-2025:15437 RHSA-2025:15435 RHSA-2025:15436

mozjs128 SLES for SAP applications 16.0, SLES 16.0 128.14.0-160000.1.1
MozillaFirefox SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES for SAP 15 SP3 +12 more 140.2.0-150200.152.198.1
MozillaThunderbird SLE Workstation Extension 15 SP7, SLE Workstation Extension 15 SP6, SLE Module for Package Hub 15 SP7 +2 more 140.2.0-150200.8.236.1
MozillaFirefox SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 140.2.0-112.276.1

suse advisories SUSE-SU-2025:21170-1 SUSE-SU-2025:03009-1 SUSE-SU-2025:03008-1 SUSE-SU-2025:03007-1

mozjs128 openSUSE Leap 16.0 128.14.0-160000.1.1
MozillaFirefox openSUSE Tumbleweed 142.0.1-1.1
mozjs128 openSUSE Tumbleweed 128.14.0-1.1
MozillaThunderbird openSUSE Tumbleweed 140.2.0-1.1
firefox-esr openSUSE Tumbleweed 140.2.0-1.1

opensuse advisories openSUSE-SU-2025:20135-1 openSUSE-SU-2025:15516-1 openSUSE-SU-2025:15494-1 openSUSE-SU-2025:15472-1 openSUSE-SU-2025:15467-1

thunderbird AlmaLinux 10 128.14.0-3.el10_0.alma.1
thunderbird AlmaLinux 8 128.14.0-3.el8_10.alma.1
thunderbird AlmaLinux 9 128.14.0-3.el9_6.alma.1
firefox AlmaLinux 9 128.14.0-2.el9_6.alma.1
firefox-x11 AlmaLinux 9 128.14.0-2.el9_6.alma.1
firefox AlmaLinux 10 128.14.0-2.el10_0
firefox AlmaLinux 8 128.14.0-2.el8_10.alma.1

almalinux advisories ALSA-2025:14844 ALSA-2025:14743 ALSA-2025:14640 ALSA-2025:14416 ALSA-2025:14417 ALSA-2025:14442

firefox Rocky Linux 9 128.14.0-2.el9_6
firefox Rocky Linux 10 128.14.0-2.el10_0
thunderbird Rocky Linux 10 128.14.0-3.el10_0
firefox Rocky Linux 8 128.14.0-2.el8_10
thunderbird Rocky Linux 8 128.14.0-3.el8_10

rocky linux advisories RLSA-2025:14416 RLSA-2025:14417 RLSA-2025:14844 RLSA-2025:14442 RLSA-2025:14743

Is CVE-2025-9181 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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-2025-9181 updated 2026-11-07 cvss 6.1

thunderbird: firefox: Uninitialized memory in the JavaScript Engine 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 firefox-flatpak, thunderbird-flatpak
affected: no fix available
Red Hat Enterprise Linux AppStream (v. 8) firefox 128.14.0-2.el8_10, thunderbird 128.14.0-3.el8_10
fixed: vendor fix RHSA-2025:14442
Red Hat Enterprise Linux AppStream (v. 9) firefox 128.14.0-2.el9_6, firefox-x11 128.14.0-2.el9_6, thunderbird 128.14.0-3.el9_6
fixed: vendor fix RHSA-2025:14416
Red Hat Enterprise Linux AppStream (v. 10) firefox 128.14.0-2.el10_0, thunderbird 128.14.0-3.el10_0
fixed: vendor fix RHSA-2025:14417
Red Hat Enterprise Linux AppStream AUS (v. 8.2) firefox 128.14.0-2.el8_2, thunderbird 128.14.0-3.el8_2
fixed: vendor fix RHSA-2025:15418
Red Hat Enterprise Linux AppStream AUS (v.8.4) firefox 128.14.0-2.el8_4, thunderbird 128.14.0-3.el8_4
fixed: vendor fix RHSA-2025:15419
Red Hat Enterprise Linux AppStream AUS (v.8.6) firefox 128.14.0-2.el8_6, thunderbird 128.14.0-3.el8_6 Red Hat Enterprise Linux AppStream E4S (v.8.6) firefox 128.14.0-2.el8_6, thunderbird 128.14.0-3.el8_6
fixed: vendor fix RHSA-2025:15422

show 8 more

Red Hat Enterprise Linux AppStream E4S (v.8.8) firefox 128.14.0-2.el8_8, thunderbird 128.14.0-3.el8_8
fixed: vendor fix RHSA-2025:15424
Red Hat Enterprise Linux AppStream E4S (v.9.0) firefox 128.14.0-2.el9_0, thunderbird 128.14.0-3.el9_0
fixed: vendor fix RHSA-2025:15420
Red Hat Enterprise Linux AppStream E4S (v.9.2) firefox 128.14.0-2.el9_2, firefox-x11 128.14.0-2.el9_2, thunderbird 128.14.0-3.el9_2
fixed: vendor fix RHSA-2025:15421
Red Hat Enterprise Linux AppStream EUS (v.9.4) firefox 128.14.0-2.el9_4, firefox-x11 128.14.0-2.el9_4, thunderbird 128.14.0-3.el9_4
fixed: vendor fix RHSA-2025:15423
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) firefox 128.14.0-2.el8_4, thunderbird 128.14.0-3.el8_4
fixed: vendor fix RHSA-2025:15419
Red Hat Enterprise Linux AppStream TUS (v.8.6) firefox 128.14.0-2.el8_6, thunderbird 128.14.0-3.el8_6
fixed: vendor fix RHSA-2025:15422
Red Hat Enterprise Linux AppStream TUS (v.8.8) firefox 128.14.0-2.el8_8, thunderbird 128.14.0-3.el8_8
fixed: vendor fix RHSA-2025:15424
Red Hat Enterprise Linux Server (v. 7 ELS) firefox 128.14.0-2.el7_9
fixed: vendor fix RHSA-2025:15430

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: partial
Assessed: last yr. (2025-08-20)

Exploit prediction

0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
CNA	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Affected products

Mozilla Firefox
Mozilla Thunderbird

Classification

Weakness

CWE-457 Use of Uninitialized Variable

References

mozilla.org /security/advisories/mfsa2025-64/
vendor-advisory
mozilla.org /security/advisories/mfsa2025-66/
vendor-advisory
mozilla.org /security/advisories/mfsa2025-67/
vendor-advisory
mozilla.org /security/advisories/mfsa2025-70/
vendor-advisory
mozilla.org /security/advisories/mfsa2025-71/
vendor-advisory
mozilla.org /security/advisories/mfsa2025-72/
vendor-advisory
bugzilla.mozilla.org /show_bug.cgi?id=1977130
issue-tracking, permissions-required
lists.debian.org /debian-lts-announce/2025/08/msg00018.html
lists.debian.org /debian-lts-announce/2025/08/msg00016.html

Sources

CVE List CVE-2025-9181
NVD CVE-2025-9181

Fencer Intel 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.

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