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Fencer Vulns
high 8.8

CVE-2023-6864 json

Memory safety bugs present in Firefox 120, Firefox ESR 115.5, and Thunderbird 115.5.

published 2023-12-19 2 y ago modified 2026-06-17 4 mo ago also EUVD-2023-59068

cvss
8.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 68%
public exploits
0
none known

Summary

Memory safety bugs present in Firefox 120, Firefox ESR 115.5, and Thunderbird 115.5. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 115.6, Thunderbird < 115.6, and Firefox < 121.

Patch / fix

  • Mozilla Firefox ESR 115.6
  • Mozilla Thunderbird 115.6
  • Mozilla Firefox 121
  • firefox-esr Debian 12 115.6.0esr-1~deb12u1
  • firefox-esr Debian 14, Debian 13 115.6.0esr-1
  • thunderbird Debian 12 1:115.6.0-1~deb12u1
  • thunderbird Debian 14, Debian 13 1:115.6.0-1

debian advisories DEBIAN-CVE-2023-6864

  • firefox Ubuntu 20.04 LTS 121.0+build1-0ubuntu0.20.04.1
  • thunderbird Ubuntu 20.04 LTS 1:115.6.0+build2-0ubuntu0.20.04.1
  • thunderbird Ubuntu 22.04 LTS 1:115.6.0+build2-0ubuntu0.22.04.1
  • thunderbird Ubuntu 24.04 LTS 1:115.6.0+build2-0ubuntu1

ubuntu advisories UBUNTU-CVE-2023-6864

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 8 115.6.0-1.el8_9
  • thunderbird RHEL 7 115.6.0-1.el7_9
  • thunderbird RHEL 9 115.6.0-1.el9_3
  • firefox RHEL 7 115.6.0-1.el7_9
  • firefox RHEL 9 115.6.0-1.el9_3
  • firefox-x11 RHEL 9 115.6.0-1.el9_3
  • firefox RHEL 8 115.6.0-1.el8_9
  • thunderbird RHEL 8.4 TUS, RHEL 8.4 E4S, RHEL 8.4 AUS 115.6.0-1.el8_4

red hat advisories RHSA-2024:0003RHSA-2024:0028RHSA-2024:0029RHSA-2024:0030RHSA-2024:0027RHSA-2024:0001

  • MozillaThunderbird SLE Workstation Extension 15 SP5, SLE Module for Package Hub 15 SP5, openSUSE Leap 15.5 115.6.0-150200.8.142.2
  • MozillaFirefox SLES for SAP 15 SP4, SLES for SAP 15 SP3, SLES for SAP 15 SP2 +14 more 115.6.0-150200.152.120.1
  • MozillaFirefox SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 115.6.0-112.194.1
  • MozillaFirefox SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLE High Performance Computing 15 SP1-LTSS 115.6.0-150000.150.119.1

suse advisories SUSE-SU-2024:0044-1SUSE-SU-2023:4929-1SUSE-SU-2023:4928-1SUSE-SU-2023:4912-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaThunderbird openSUSE Tumbleweed 115.6.0-1.1
  • MozillaFirefox openSUSE Tumbleweed 121.0-1.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:13519-1openSUSE-SU-2024:13531-1

  • thunderbird AlmaLinux 9 115.6.0-1.el9_3.alma
  • thunderbird AlmaLinux 8 115.6.0-1.el8_9.alma
  • firefox AlmaLinux 8 115.6.0-1.el8_9.alma
  • firefox AlmaLinux 9 115.6.0-1.el9_3.alma
  • firefox-x11 AlmaLinux 9 115.6.0-1.el9_3.alma

almalinux advisories ALSA-2024:0001ALSA-2024:0003ALSA-2024:0012ALSA-2024:0025

  • thunderbird Rocky Linux 8 115.6.0-1.el8_9
  • firefox Rocky Linux 8 115.6.0-1.el8_9

rocky linux advisories RLSA-2024:0003RLSA-2024:0012

  • mozjs Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 115.6.0-r0
  • mozjs115 Alpine 3.20, Alpine 3.19 115.6.0-r0
  • firefox-esr Alpine 3.23, Alpine 3.22, Alpine 3.21 +3 more 115.6.0-r0

alpine advisories ALPINE-CVE-2023-6864

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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-2023-6864 updated cvss 8.8

Mozilla: Memory safety bugs fixed in Firefox 121, Firefox ESR 115.6, and Thunderbird 115.6

  • Red Hat Enterprise Linux 6 firefox, thunderbird
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) firefox 115.6.0-1.el8_9, thunderbird 115.6.0-1.el8_9
    fixed: vendor fix RHSA-2024:0012
  • Red Hat Enterprise Linux AppStream (v. 9) firefox 115.6.0-1.el9_3, firefox-x11 115.6.0-1.el9_3, thunderbird 115.6.0-1.el9_3
    fixed: vendor fix RHSA-2024:0025
  • Red Hat Enterprise Linux AppStream AUS (v. 8.2) firefox 115.6.0-1.el8_2, thunderbird 115.6.0-1.el8_2
    fixed: vendor fix RHSA-2024:0023
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) firefox 115.6.0-1.el8_4, thunderbird 115.6.0-1.el8_4
    fixed: vendor fix RHSA-2024:0021
  • Red Hat Enterprise Linux AppStream E4S (v. 8.2) firefox 115.6.0-1.el8_2, thunderbird 115.6.0-1.el8_2
    fixed: vendor fix RHSA-2024:0023
  • Red Hat Enterprise Linux AppStream E4S (v.8.4) firefox 115.6.0-1.el8_4, thunderbird 115.6.0-1.el8_4
    fixed: vendor fix RHSA-2024:0021
  • Red Hat Enterprise Linux AppStream EUS (v.8.6) firefox 115.6.0-1.el8_6, thunderbird 115.6.0-1.el8_6
    fixed: vendor fix RHSA-2024:0024
show 6 more
  • Red Hat Enterprise Linux AppStream EUS (v.8.8) firefox 115.6.0-1.el8_8, thunderbird 115.6.0-1.el8_8
    fixed: vendor fix RHSA-2024:0011
  • Red Hat Enterprise Linux AppStream EUS (v.9.0) firefox 115.6.0-1.el9_0, thunderbird 115.6.0-1.el9_0
    fixed: vendor fix RHSA-2024:0022
  • Red Hat Enterprise Linux AppStream EUS (v.9.2) firefox 115.6.0-1.el9_2, firefox-x11 115.6.0-1.el9_2, thunderbird 115.6.0-1.el9_2
    fixed: vendor fix RHSA-2024:0019
  • Red Hat Enterprise Linux AppStream TUS (v. 8.2) firefox 115.6.0-1.el8_2, thunderbird 115.6.0-1.el8_2
    fixed: vendor fix RHSA-2024:0023
  • Red Hat Enterprise Linux AppStream TUS (v.8.4) firefox 115.6.0-1.el8_4, thunderbird 115.6.0-1.el8_4
    fixed: vendor fix RHSA-2024:0021
  • Red Hat Enterprise Linux Client (v. 7) firefox 115.6.0-1.el7_9, thunderbird 115.6.0-1.el7_9 Red Hat Enterprise Linux Client Optional (v. 7) firefox 115.6.0-1.el7_9 Red Hat Enterprise Linux Server (v. 7) firefox 115.6.0-1.el7_9 Red Hat Enterprise Linux Server Optional (v. 7) firefox 115.6.0-1.el7_9, thunderbird 115.6.0-1.el7_9 Red Hat Enterprise Linux Workstation (v. 7) firefox 115.6.0-1.el7_9, thunderbird 115.6.0-1.el7_9 Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 115.6.0-1.el7_9
    fixed: vendor fix RHSA-2024:0026

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

Exploit prediction

1.19% chance of exploitation in the next 30 days, higher than 68% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

  • Mozilla Firefox ESR
  • Mozilla Thunderbird
  • Mozilla Firefox

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.