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Fencer Intel
high 8.1

CVE-2018-5178 json

A buffer overflow was found during UTF8 to Unicode string conversion within JavaScript with extremely large amounts of data.

published 2018-06-11 8 y ago modified 2026-06-17 4 mo ago also EUVD-2018-16963

cvss
8.1
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
4.9%
EPSS 4.9% chance of exploitation in 30 days, percentile 92%
public exploits
0
none known

Summary

A buffer overflow was found during UTF8 to Unicode string conversion within JavaScript with extremely large amounts of data. This vulnerability requires the use of a malicious or vulnerable legacy extension in order to occur. This vulnerability affects Thunderbird ESR < 52.8, Thunderbird < 52.8, and Firefox ESR < 52.8.

Patch / fix

  • Mozilla Thunderbird ESR 52.8
  • Mozilla Thunderbird 52.8
  • Mozilla Firefox ESR 52.8
  • firefox-esr Debian 14, Debian 13, Debian 12 52.8.0esr-1
  • thunderbird Debian 14, Debian 13, Debian 12 1:52.8.0-1

debian advisories DEBIAN-CVE-2018-5178

  • thunderbird Ubuntu 14.04 LTS 1:52.8.0+build1-0ubuntu0.14.04.1
  • thunderbird Ubuntu 16.04 LTS 1:52.8.0+build1-0ubuntu0.16.04.1
  • thunderbird Ubuntu 18.04 LTS 1:52.8.0+build1-0ubuntu0.18.04.1

ubuntu advisories UBUNTU-CVE-2018-5178

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 6 52.8.0-2.el6_9
  • thunderbird RHEL 7 52.8.0-1.el7_5
  • firefox RHEL 6 52.8.0-1.el6_9
  • firefox RHEL 7 52.8.0-1.el7_5

red hat advisories RHSA-2018:1726RHSA-2018:1725RHSA-2018:1414RHSA-2018:1415

  • MozillaFirefox SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +17 more 68.2.0-109.95.2
  • MozillaFirefox SLES 12 SP3, SLES 12 SP2-BCL, SLED 12 SP3 +9 more 52.8.0esr-109.31.2
  • MozillaFirefox SLE Module for Desktop Applications 15 52.9.0esr-3.7.12
  • MozillaFirefox SLES for SAP 11 SP4, SLES 11 SP4, SLES 11 SP3-TERADATA +3 more 52.8.0esr-72.32.1

suse advisories SUSE-SU-2019:2872-1SUSE-SU-2018:1334-2SUSE-SU-2018:2298-1SUSE-SU-2018:1334-1SUSE-SU-2018:1319-1

  • MozillaThunderbird openSUSE Tumbleweed 91.1.1-1.1

opensuse advisories openSUSE-SU-2024:10601-1

  • thunderbird Arch Linux 52.8.0-1

arch linux advisories AVG-707

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-2018-5178 updated cvss 8.1

Mozilla: Buffer overflow during UTF-8 to Unicode string conversion through legacy extension

  • Red Hat Enterprise Linux Client (v. 7) firefox 52.8.0-1.el7_5, thunderbird 52.8.0-1.el7_5 Red Hat Enterprise Linux Client Optional (v. 7) firefox 52.8.0-1.el7_5
    fixed: vendor fix RHSA-2018:1415
  • Red Hat Enterprise Linux Desktop (v. 6) firefox 52.8.0-1.el6_9, thunderbird 52.8.0-2.el6_9 Red Hat Enterprise Linux Desktop Optional (v. 6) firefox 52.8.0-1.el6_9
    fixed: vendor fix RHSA-2018:1414
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) firefox 52.8.0-1.el7_5 Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) firefox 52.8.0-1.el7_5, thunderbird 52.8.0-1.el7_5
    fixed: vendor fix RHSA-2018:1415
  • Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox 52.8.0-1.el6_9 Red Hat Enterprise Linux Server (v. 6) firefox 52.8.0-1.el6_9
    fixed: vendor fix RHSA-2018:1414
  • Red Hat Enterprise Linux Server (v. 7) firefox 52.8.0-1.el7_5
    fixed: vendor fix RHSA-2018:1415
  • Red Hat Enterprise Linux Server Optional (v. 6) firefox 52.8.0-1.el6_9, thunderbird 52.8.0-2.el6_9
    fixed: vendor fix RHSA-2018:1414
  • Red Hat Enterprise Linux Server Optional (v. 7) firefox 52.8.0-1.el7_5, thunderbird 52.8.0-1.el7_5
    fixed: vendor fix RHSA-2018:1415
  • Red Hat Enterprise Linux Workstation (v. 6) firefox 52.8.0-1.el6_9, thunderbird 52.8.0-2.el6_9
    fixed: vendor fix RHSA-2018:1414
show 4 more
  • Red Hat Enterprise Linux Workstation (v. 7) firefox 52.8.0-1.el7_5, thunderbird 52.8.0-1.el7_5
    fixed: vendor fix RHSA-2018:1415
  • Red Hat Enterprise Linux Workstation Optional (v. 6) firefox 52.8.0-1.el6_9
    fixed: vendor fix RHSA-2018:1414
  • Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 52.8.0-1.el7_5
    fixed: vendor fix RHSA-2018:1415
  • Red Hat Enterprise Linux 8 firefox, thunderbird
    not affected: vulnerable code not present

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

4.89% chance of exploitation in the next 30 days, higher than 92% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 8.1 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Affected products

  • Mozilla Thunderbird ESR
  • Mozilla Thunderbird
  • Mozilla Firefox ESR

Classification

Weakness
  • CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

References

Sources

Fencer Intel 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.