high 8.1

CVE-2025-4093 json

Memory safety bug fixed in Firefox ESR 128.10 and Thunderbird 128.10

published 2025-04-29 18 mo ago modified 2026-10-05 34 d ago also EUVD-2025-12642

cvss: 8.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits: 0; none known

Memory safety bug present in Firefox ESR 128.9, and Thunderbird 128.9. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox ESR 128.10 and Thunderbird 128.10.

Patch / fix

fixed in 4 distros 7

mozilla firefox 128.10
mozilla firefox_esr 128.10
mozilla thunderbird 128.10
mozilla thunderbird_esr 128.10

debian ubuntu red hat suse opensuse almalinux rocky linux

firefox-esr Debian 12 128.10.0esr-1~deb12u1
firefox-esr Debian 14, Debian 13 128.10.0esr-1
thunderbird Debian 12 1:128.10.0esr-1~deb12u1
thunderbird Debian 14, Debian 13 1:128.10.0esr-1

debian advisories DEBIAN-CVE-2025-4093

thunderbird Ubuntu 22.04 LTS 1:128.12.0+build1-0ubuntu0.22.04.1

ubuntu advisories UBUNTU-CVE-2025-4093

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 10.0 128.10.0-1.el10_0
firefox RHEL 10.0 128.10.0-1.el10_0
firefox RHEL 9 128.10.0-1.el9_6
firefox-x11 RHEL 9 128.10.0-1.el9_6
thunderbird RHEL 8 128.10.0-1.el8_10
thunderbird RHEL 9 128.10.0-1.el9_5
firefox RHEL 8 128.10.0-1.el8_10
firefox RHEL 9 128.10.0-1.el9_5

red hat advisories RHSA-2025:7695 RHSA-2025:7694 RHSA-2025:7693 RHSA-2025:7691 RHSA-2025:7692 RHSA-2025:7690

MozillaThunderbird SLE Workstation Extension 15 SP6, SLE Module for Package Hub 15 SP6, openSUSE Leap 15.6 128.10.0-150200.8.212.1
MozillaFirefox SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES for SAP 15 SP3 +11 more 128.10.0-150200.152.179.1

suse advisories SUSE-SU-2025:1506-1 SUSE-SU-2025:1436-1

MozillaThunderbird openSUSE Tumbleweed 128.10.0-1.1

opensuse advisories openSUSE-SU-2025:15042-1

firefox AlmaLinux 9 128.10.0-1.el9_6.alma.1
firefox-x11 AlmaLinux 9 128.10.0-1.el9_6.alma.1
firefox AlmaLinux 10 128.10.0-1.el10_0
thunderbird AlmaLinux 10 128.10.0-1.el10_0.alma.1
thunderbird AlmaLinux 8 128.10.0-1.el8_10.alma.1
firefox AlmaLinux 9 128.10.0-1.el9_5.alma.1
firefox-x11 AlmaLinux 9 128.10.0-1.el9_5.alma.1
firefox AlmaLinux 8 128.10.0-1.el8_10.alma.1

almalinux advisories ALSA-2025:7428 ALSA-2025:7506 ALSA-2025:7507 ALSA-2025:4797 ALSA-2025:4443 ALSA-2025:4458

firefox Rocky Linux 9 128.10.0-1.el9_5
thunderbird Rocky Linux 9 128.10.0-1.el9_5
firefox Rocky Linux 8 128.10.0-1.el8_10
thunderbird Rocky Linux 8 128.10.0-1.el8_10

rocky linux advisories RLSA-2025:4443 RLSA-2025:4460 RLSA-2025:7428 RLSA-2025:4458 RLSA-2025:4797

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-2025-4093 updated 2026-11-04 cvss 8.8

firefox: thunderbird: Memory safety bug fixed in Firefox ESR 128.10 and Thunderbird 128.10

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 9 firefox-flatpak-container, thunderbird-flatpak-container Red Hat Enterprise Linux 10 firefox-flatpak-container, thunderbird-flatpak-container
affected: no fix available
Red Hat Enterprise Linux AppStream (v. 8) firefox 128.10.0-1.el8_10, thunderbird 128.10.0-1.el8_10
fixed: vendor fix RHSA-2025:4458
Red Hat Enterprise Linux AppStream (v. 9) firefox 128.10.0-1.el9_5, firefox 128.10.0-1.el9_6, firefox-x11 128.10.0-1.el9_5, firefox-x11 128.10.0-1.el9_6, thunderbird 128.10.0-1.el9_5
fixed: vendor fix RHSA-2025:4443
Red Hat Enterprise Linux AppStream (v. 10) firefox 128.10.0-1.el10_0, thunderbird 128.10.0-1.el10_0
fixed: vendor fix RHSA-2025:7506
Red Hat Enterprise Linux AppStream AUS (v. 8.2) firefox 128.10.0-1.el8_2, thunderbird 128.10.0-1.el8_2
fixed: vendor fix RHSA-2025:7547
Red Hat Enterprise Linux AppStream AUS (v.8.4) firefox 128.10.0-1.el8_4, thunderbird 128.10.0-1.el8_4
fixed: vendor fix RHSA-2025:7545
Red Hat Enterprise Linux AppStream AUS (v.8.6) firefox 128.10.0-1.el8_6, thunderbird 128.10.0-1.el8_6
fixed: vendor fix RHSA-2025:7544

show 9 more

Red Hat Enterprise Linux AppStream E4S (v.8.4) firefox 128.10.0-1.el8_4, thunderbird 128.10.0-1.el8_4
fixed: vendor fix RHSA-2025:7545
Red Hat Enterprise Linux AppStream E4S (v.8.6) firefox 128.10.0-1.el8_6, thunderbird 128.10.0-1.el8_6
fixed: vendor fix RHSA-2025:7544
Red Hat Enterprise Linux AppStream E4S (v.9.0) firefox 128.10.0-1.el9_0, thunderbird 128.10.0-1.el9_0
fixed: vendor fix RHSA-2025:4753
Red Hat Enterprise Linux AppStream EUS (v.8.8) firefox 128.10.0-1.el8_8, thunderbird 128.10.0-1.el8_8
fixed: vendor fix RHSA-2025:7543
Red Hat Enterprise Linux AppStream EUS (v.9.2) firefox 128.10.0-1.el9_2, firefox-x11 128.10.0-1.el9_2, thunderbird 128.10.0-1.el9_2
fixed: vendor fix RHSA-2025:4752
Red Hat Enterprise Linux AppStream EUS (v.9.4) firefox 128.10.0-1.el9_4, firefox-x11 128.10.0-1.el9_4, thunderbird 128.10.0-1.el9_4
fixed: vendor fix RHSA-2025:4756
Red Hat Enterprise Linux AppStream TUS (v.8.4) firefox 128.10.0-1.el8_4, thunderbird 128.10.0-1.el8_4
fixed: vendor fix RHSA-2025:7545
Red Hat Enterprise Linux AppStream TUS (v.8.6) firefox 128.10.0-1.el8_6, thunderbird 128.10.0-1.el8_6
fixed: vendor fix RHSA-2025:7544
Red Hat Enterprise Linux Server (v. 7 ELS) firefox 128.10.0-1.el7_9
fixed: vendor fix RHSA-2025:4751

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: 18 mo ago (2025-04-29)

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% 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/mfsa2025-29/
vendor-advisory
mozilla.org /security/advisories/mfsa2025-32/
vendor-advisory
bugzilla.mozilla.org /show_bug.cgi?id=1894100
permissions-required
lists.debian.org /debian-lts-announce/2025/05/msg00024.html

Sources

CVE List CVE-2025-4093
NVD CVE-2025-4093

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