critical 9.8

CVE-2025-1012 json

Use-after-free during concurrent delazification

published 2025-02-04 21 mo ago modified 2026-10-05 34 d ago also EUVD-2025-1967

cvss: 9.8; 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 39%
public exploits: 0; none known

A race during concurrent delazification could have led to a use-after-free. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.

Patch / fix

fixed in 3 distros 7

mozilla firefox 115.20, 128.7, 135
mozilla firefox_esr 115.20, 128.7, 135
mozilla thunderbird 128.7, 135

debian ubuntu red hat suse opensuse almalinux rocky linux

firefox-esr Debian 12 128.7.0esr-1~deb12u1
firefox-esr Debian 14, Debian 13 128.7.0esr-1
thunderbird Debian 12 1:128.7.0esr-1~deb12u1
thunderbird Debian 14, Debian 13 1:128.7.0esr-1

debian advisories DEBIAN-CVE-2025-1012

firefox Ubuntu 20.04 LTS 135.0+build2-0ubuntu0.20.04.1
thunderbird Ubuntu 22.04 LTS 1:128.12.0+build1-0ubuntu0.22.04.1

ubuntu advisories UBUNTU-CVE-2025-1012

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 8 128.7.0-1.el8_10
firefox RHEL 8 128.7.0-1.el8_10
thunderbird RHEL 9 128.7.0-1.el9_5
firefox RHEL 9 128.7.0-1.el9_5
firefox-x11 RHEL 9 128.7.0-1.el9_5
thunderbird RHEL 8.2 AUS 128.7.0-1.el8_2
thunderbird RHEL 8.8 EUS 128.7.0-1.el8_8
thunderbird RHEL 8.6 TUS, RHEL 8.6 E4S, RHEL 8.6 AUS 128.7.0-1.el8_6

red hat advisories RHSA-2025:1348 RHSA-2025:1340 RHSA-2025:1341 RHSA-2025:1339 RHSA-2025:1319 RHSA-2025:1317

MozillaThunderbird SLE Workstation Extension 15 SP6, SLE Module for Package Hub 15 SP6, openSUSE Leap 15.6 128.7.0-150200.8.200.1
MozillaFirefox SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES for SAP 15 SP3 +11 more 128.7.0-150200.152.170.1
MozillaFirefox SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 128.7.0-112.246.1

suse advisories SUSE-SU-2025:0405-1 SUSE-SU-2025:0391-1 SUSE-SU-2025:0374-1

MozillaFirefox openSUSE Tumbleweed 135.0-1.1
MozillaThunderbird openSUSE Tumbleweed 128.7.0-1.1
firefox-esr openSUSE Tumbleweed 128.7.0-1.1

opensuse advisories openSUSE-SU-2025:14730-1 openSUSE-SU-2025:14731-1 openSUSE-SU-2025:14727-1

firefox AlmaLinux 8 128.7.0-1.el8_10
thunderbird AlmaLinux 8 128.7.0-1.el8_10.alma.1
thunderbird AlmaLinux 9 128.7.0-1.el9_5.alma.1
firefox AlmaLinux 9 128.7.0-1.el9_5
firefox-x11 AlmaLinux 9 128.7.0-1.el9_5

almalinux advisories ALSA-2025:1283 ALSA-2025:1292 ALSA-2025:1184 ALSA-2025:1066

firefox Rocky Linux 8 128.7.0-1.el8_10
thunderbird Rocky Linux 8 128.7.0-1.el8_10

rocky linux advisories RLSA-2025:1283 RLSA-2025:1292

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-2025-1012 updated 2026-11-05 cvss 7.6

firefox: thunderbird: Use-after-free during concurrent delazification

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, thunderbird, firefox-flatpak-container, thunderbird-flatpak-container
affected: no fix available
Red Hat Enterprise Linux AppStream (v. 8) firefox 128.7.0-1.el8_10, thunderbird 128.7.0-1.el8_10
fixed: vendor fix RHSA-2025:1283
Red Hat Enterprise Linux AppStream (v. 9) firefox 128.7.0-1.el9_5, firefox-x11 128.7.0-1.el9_5, thunderbird 128.7.0-1.el9_5
fixed: vendor fix RHSA-2025:1066
Red Hat Enterprise Linux AppStream AUS (v. 8.2) firefox 128.7.0-1.el8_2, thunderbird 128.7.0-1.el8_2
fixed: vendor fix RHSA-2025:1133
Red Hat Enterprise Linux AppStream AUS (v.8.4) firefox 128.7.0-1.el8_4, thunderbird 128.7.0-1.el8_4
fixed: vendor fix RHSA-2025:1135
Red Hat Enterprise Linux AppStream AUS (v.8.6) firefox 128.7.0-1.el8_6, thunderbird 128.7.0-1.el8_6
fixed: vendor fix RHSA-2025:1136
Red Hat Enterprise Linux AppStream E4S (v.8.4) firefox 128.7.0-1.el8_4, thunderbird 128.7.0-1.el8_4
fixed: vendor fix RHSA-2025:1135

show 8 more

Red Hat Enterprise Linux AppStream E4S (v.8.6) firefox 128.7.0-1.el8_6, thunderbird 128.7.0-1.el8_6
fixed: vendor fix RHSA-2025:1136
Red Hat Enterprise Linux AppStream E4S (v.9.0) firefox 128.7.0-1.el9_0, thunderbird 128.7.0-1.el9_0
fixed: vendor fix RHSA-2025:1138
Red Hat Enterprise Linux AppStream EUS (v.8.8) firefox 128.7.0-1.el8_8, thunderbird 128.7.0-1.el8_8
fixed: vendor fix RHSA-2025:1137
Red Hat Enterprise Linux AppStream EUS (v.9.2) firefox 128.7.0-1.el9_2, firefox-x11 128.7.0-1.el9_2, thunderbird 128.7.0-1.el9_2
fixed: vendor fix RHSA-2025:1139
Red Hat Enterprise Linux AppStream EUS (v.9.4) firefox 128.7.0-1.el9_4, firefox-x11 128.7.0-1.el9_4, thunderbird 128.7.0-1.el9_4
fixed: vendor fix RHSA-2025:1140
Red Hat Enterprise Linux AppStream TUS (v.8.4) firefox 128.7.0-1.el8_4, thunderbird 128.7.0-1.el8_4
fixed: vendor fix RHSA-2025:1135
Red Hat Enterprise Linux AppStream TUS (v.8.6) firefox 128.7.0-1.el8_6, thunderbird 128.7.0-1.el8_6
fixed: vendor fix RHSA-2025:1136
Red Hat Enterprise Linux Server (v. 7 ELS) firefox 128.7.0-1.el7_9
fixed: vendor fix RHSA-2025:1132

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: yes
Technical impact: total
Assessed: 21 mo ago (2025-02-05)

Exploit prediction

0.45% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	3.1	7.5	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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/mfsa2025-07/
vendor-advisory
mozilla.org /security/advisories/mfsa2025-08/
vendor-advisory
mozilla.org /security/advisories/mfsa2025-09/
vendor-advisory
mozilla.org /security/advisories/mfsa2025-10/
vendor-advisory
mozilla.org /security/advisories/mfsa2025-11/
vendor-advisory
bugzilla.mozilla.org /show_bug.cgi?id=1939710
permissions-required
lists.debian.org /debian-lts-announce/2025/02/msg00006.html
lists.debian.org /debian-lts-announce/2025/02/msg00005.html

Sources

CVE List CVE-2025-1012
NVD CVE-2025-1012

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