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Fencer Vulns
medium 5.4

CVE-2026-109729 json

Use-after-free in the JavaScript Engine: JIT component

published 2026-10-13 27 d ago modified 2026-10-13 26 d ago also EUVD-2026-98647

cvss
5.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits
0
none known

Summary

Use-after-free in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 158, Firefox ESR 115.43, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

Patch / fix

  • mozilla firefox 115.43, 153.5, 158
  • mozilla firefox_esr 115.43, 153.5, 158
  • mozilla thunderbird 153.5, 158
  • mozilla thunderbird_esr 153.5, 158
  • firefox-esr Debian 12 153.5.0esr-1~deb12u1
  • firefox-esr Debian 13 153.5.0esr-1~deb13u1
  • firefox-esr Debian 14 153.5.0esr-1
  • thunderbird Debian 12 1:153.5.1esr-1~deb12u1
  • thunderbird Debian 13 1:153.5.1esr-1~deb13u1
  • thunderbird Debian 14 1:153.5.0esr-1

debian advisories DEBIAN-CVE-2026-109729

  • MozillaFirefox SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 153.5.0-150400.157.16.1
  • MozillaFirefox SLES for SAP applications 16.0, SLES 16.0 153.5.0-160000.1.1
  • MozillaThunderbird SLE Workstation Extension 15 SP7, SLE Module for Package Hub 15 SP7 153.5.0-150400.13.9.1
  • MozillaFirefox SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 153.5.0-118.16.2

suse advisories SUSE-SU-2026:4834-1SUSE-SU-2026:4806-1SUSE-SU-2026:24260-1SUSE-SU-2026:4736-1

  • MozillaThunderbird openSUSE Tumbleweed 153.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 158.0-1.1
  • MozillaFirefox openSUSE Leap 16.0 153.5.0-160000.1.1
  • firefox-esr openSUSE Tumbleweed 153.5.0-1.1

opensuse advisories openSUSE-SU-2026:12224-1openSUSE-SU-2026:12190-1openSUSE-SU-2026:22139-1openSUSE-SU-2026:12116-1

  • thunderbird AlmaLinux 9 153.5.0-1.el9_8.alma.1
  • firefox AlmaLinux 8 153.5.0-1.el8_10
  • firefox AlmaLinux 9 153.5.0-1.el9_8
  • firefox-x11 AlmaLinux 9 153.5.0-1.el9_8
  • firefox AlmaLinux 10 153.5.0-1.el10_2

almalinux advisories ALSA-2026:93443ALSA-2026:89756ALSA-2026:89757ALSA-2026:89758

  • thunderbird Rocky Linux 9 153.5.0-1.el9_8
  • firefox Rocky Linux 10 153.5.0-1.el10_2
  • firefox Rocky Linux 9 153.5.0-1.el9_8
  • firefox Rocky Linux 8 153.5.0-1.el8_10

rocky linux advisories RLSA-2026:93443RLSA-2026:89758RLSA-2026:89757RLSA-2026:89756

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-2026-109729 updated cvss 7.5

firefox: Use-after-free in the JavaScript Engine: JIT component

  • Red Hat Enterprise Linux 6 firefox, thunderbird
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 firefox, thunderbird
    affected: no fix available, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 thunderbird Red Hat Enterprise Linux 10 thunderbird, rhel10/firefox-flatpak, rhel10/thunderbird-flatpak
    affected: no fix available
  • Red Hat Enterprise Linux AppStream (v. 8) firefox 153.5.0-1.el8_10
    fixed: vendor fix RHSA-2026:89756
  • Red Hat Enterprise Linux AppStream (v. 9) firefox 153.5.0-1.el9_8, firefox-x11 153.5.0-1.el9_8, thunderbird 153.5.0-1.el9_8
    fixed: vendor fix RHSA-2026:89757
  • Red Hat Enterprise Linux AppStream (v. 10) firefox 153.5.0-1.el10_2
    fixed: vendor fix RHSA-2026:89758
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) thunderbird 153.5.0-1.el9_4
    fixed: vendor fix RHSA-2026:95597
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) thunderbird 153.5.0-1.el9_6
    fixed: vendor fix RHSA-2026:95596

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
27 d ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Affected products

  • Mozilla Firefox
  • Mozilla Thunderbird

Classification

Weakness

References

Sources

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.