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CVE-2026-124876 mozilla: Use After Free

8.8 highEPSS 0.4%Fix available

High (8.8) in mozilla. EPSS 0.4% estimated probability of exploitation activity in the next 30 days.

On this page
Use-after-free in the CSS Parsing and Computation component. This vulnerability was fixed in Firefox 160, Firefox ESR 115.45, Firefox ESR 153.7, Thunderbird 160, and Thunderbird 153.7.

Severity

CVSS 3.1

8.8 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS
0.4% estimated probability of exploitation activity in the next 30 days; 34th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
CISA's assessment (SSVC)
Exploitation: none · Automatable: no · Technical impact: total, assessed 2026-11-10. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
CWE
CWE-416 Use After Free
Published
Modified
Assigned by
mozilla (CNA)
NVD analysis
Deferred: the NVD does not plan to analyze it
Record from
the NVD, synced

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CVE-2026-124876

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Affected

Versions

From the CNA's record in the CVE List.

Fixed in

ProductRelease lineFixed in
Mozilla Firefox115115.45
Mozilla Firefox153153.7
Mozilla Firefoxlater releases160
Mozilla Thunderbird153153.7
Mozilla Thunderbirdlater releases160

Fix and patched versions

  • Mozilla Firefox: fixed in 115.45
  • Mozilla Firefox: fixed in 153.7
  • Mozilla Firefox: fixed in 160
  • Mozilla Thunderbird: fixed in 153.7
  • Mozilla Thunderbird: fixed in 160
  • Debian, Red Hat, SUSE, openSUSE, AlmaLinux, Rocky Linux: fixed package versions per release

Linux distributions

DistributionReleasePackageFixed inAdvisory
Debian12firefox-esr153.7.0esr-1~deb12u1DEBIAN-CVE-2026-124876
Debian12thunderbird1:153.7.0esr-1~deb12u1DEBIAN-CVE-2026-124876
Debian13firefox-esr153.7.0esr-1~deb13u1DEBIAN-CVE-2026-124876
Debian13thunderbird1:153.7.0esr-1~deb13u1DEBIAN-CVE-2026-124876
Debian14firefox-esr, thunderbirdno fix listedDEBIAN-CVE-2026-124876
Ubuntu18.04:LTSmozjs38, mozjs52no fix listedUBUNTU-CVE-2026-124876
Ubuntu20.04:LTSmozjs52, mozjs68no fix listedUBUNTU-CVE-2026-124876
Ubuntu22.04:LTSmozjs78, mozjs91, mozjs102 and 1 moreno fix listedUBUNTU-CVE-2026-124876
Ubuntu24.04:LTSmozjs102, mozjs115no fix listedUBUNTU-CVE-2026-124876
Red Hatenterprise_linux:8::appstreamfirefox, firefox-debuginfo, firefox-debugsource0:153.7.0-1.el8_10RHSA-2026:99112
Red Hatenterprise_linux:9::appstreamfirefox, firefox-x11, firefox-debuginfo and 1 more0:153.7.0-1.el9_9RHSA-2026:99111
Red Hatenterprise_linux:10.3firefox, firefox-debuginfo, firefox-debugsource0:153.7.0-1.el10_3RHSA-2026:99572
Red Hatenterprise_linux_eus:10.2firefox, firefox-debuginfo, firefox-debugsource0:153.7.0-1.el10_2RHSA-2026:99571
Red Hatrhel_eus:9.8::appstreamfirefox, firefox-x11, firefox-debuginfo and 1 more0:153.7.0-1.el9_8RHSA-2026:99110
SUSELinux Enterprise High Performance Computing 15 SP4-ESPOS, Linux Enterprise High Performance Computing 15 SP4-LTSS, Linux Enterprise High Performance Computing 15 SP5-ESPOS and 8 moreMozillaFirefox153.7.0-150400.157.22.1SUSE-SU-2026:5229-1
SUSELinux Enterprise Server 12 SP5-LTSS, Linux Enterprise Server LTSS Extended Security 12 SP5MozillaFirefox153.7.0-118.22.1SUSE-SU-2026:5174-1
openSUSETumbleweedfirefox-esr153.7.0-1.1openSUSE-SU-2026:12527-1
AlmaLinux8firefox153.7.0-1.el8_10ALSA-2026:99112
Rocky Linux8firefox, firefox-debuginfo, firefox-debugsource0:153.7.0-1.el8_10RLSA-2026:99112
Rocky Linux9firefox, firefox-x11, firefox-debuginfo and 1 more0:153.7.0-1.el9_9RLSA-2026:99111

From the distributions' data via OSV.dev: the Debian Security Tracker; Ubuntu Security Notices © Canonical Ltd., CC BY-SA 4.0; Red Hat Security Data © Red Hat, Inc., CC BY 4.0; SUSE security data, CC BY 4.0; AlmaLinux's OSV database, MIT; Rocky Linux's errata, BSD-3-Clause. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Debian · Ubuntu · Red Hat · SUSE · openSUSE.

Red Hat

Red Hat rates this Important.

Red Hat's statement

Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.

Red Hat's mitigation

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

ProductPackageStateAdvisory
Red Hat Enterprise Linux 8firefox-0:153.7.0-1.el8_10Fixed 2026-11-11RHSA-2026:99112
Red Hat Enterprise Linux 9firefox-0:153.7.0-1.el9_9Fixed 2026-11-11RHSA-2026:99111
Red Hat Enterprise Linux 9.8 Extended Update Supportfirefox-0:153.7.0-1.el9_8Fixed 2026-11-11RHSA-2026:99110
Red Hat Enterprise Linux 10firefoxAffected
Red Hat Enterprise Linux 10rhel10/firefox-flatpakAffected
Red Hat Enterprise Linux 10rhel10/thunderbird-flatpakAffected
Red Hat Enterprise Linux 10thunderbirdAffected
Red Hat Enterprise Linux 6firefoxOut of support scope
Red Hat Enterprise Linux 6thunderbirdOut of support scope
Red Hat Enterprise Linux 7firefoxAffected
Red Hat Enterprise Linux 7thunderbirdOut of support scope
Red Hat Enterprise Linux 8thunderbirdAffected
Red Hat Enterprise Linux 9thunderbirdAffected

Contains Red Hat Security Data © Red Hat, Inc., licensed under CC BY 4.0. Source: https://access.redhat.com/security/data. Modified: reformatted. Red Hat's page for CVE-2026-124876.

History

  1. Scored 8.8 high
  2. The NVD deferred its analysis

Changes since this site first stored the record. The same for every record: /api/public/changes.

References

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