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Fencer Vulns
critical 9.8

CVE-2018-18500 in the critical feed json

A use-after-free vulnerability can occur while parsing an HTML5 stream in concert with custom HTML elements.

published 2019-02-05 7 y ago modified 2026-06-17 4 mo ago also EUVD-2018-10225

cvss
9.8
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
12.7%
EPSS 12.7% chance of exploitation in 30 days, percentile 96%
public exploits
0
none known

Summary

A use-after-free vulnerability can occur while parsing an HTML5 stream in concert with custom HTML elements. This results in the stream parser object being freed while still in use, leading to a potentially exploitable crash. This vulnerability affects Thunderbird < 60.5, Firefox ESR < 60.5, and Firefox < 65.

Patch / fix

  • mozilla firefox 65.0
  • mozilla firefox_esr 60.5
  • mozilla thunderbird 60.5
  • firefox-esr Debian 14, Debian 13, Debian 12 60.5.0esr-1
  • thunderbird Debian 14, Debian 13, Debian 12 1:60.5.0-1

debian advisories DEBIAN-CVE-2018-18500

  • firefox Ubuntu 14.04 LTS 65.0+build2-0ubuntu0.14.04.1
  • firefox Ubuntu 16.04 LTS 65.0+build2-0ubuntu0.16.04.1
  • firefox Ubuntu 18.04 LTS 65.0+build2-0ubuntu0.18.04.1
  • thunderbird Ubuntu 14.04 LTS 1:60.5.1+build2-0ubuntu0.14.04.1
  • thunderbird Ubuntu 16.04 LTS 1:60.5.1+build2-0ubuntu0.16.04.1
  • thunderbird Ubuntu 18.04 LTS 1:60.5.1+build2-0ubuntu0.18.04.1

ubuntu advisories UBUNTU-CVE-2018-18500

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 7 60.5.0-1.el7_6
  • thunderbird RHEL 6 60.5.0-1.el6_10
  • firefox RHEL 6 60.5.0-2.el6
  • firefox RHEL 7 60.5.0-2.el7

red hat advisories RHSA-2019:0270RHSA-2019:0269RHSA-2019:0218RHSA-2019:0219

  • MozillaFirefox SLES 12 SP4, SLES 12 SP3, SLES 12 SP2-BCL +13 more 60.5.0esr-109.58.3
  • mozilla-nss SLES 12 SP4, SLES 12 SP3, SLES 12 SP2-BCL +13 more 3.41.1-58.25.1
  • MozillaFirefox-branding-SLE SLES 12 SP4, SLES 12 SP3, SLES 12 SP2-BCL +11 more 60-32.5.1
  • MozillaThunderbird SLE Workstation Extension 15 60.5.0-3.20.2
  • MozillaFirefox SLE Module for Desktop Applications 15 60.5.0-3.24.2
  • mozilla-nss SLE Module for Basesystem 15 3.41.1-3.13.1

suse advisories SUSE-SU-2019:0336-2SUSE-SU-2019:0338-1SUSE-SU-2019:0336-1SUSE-SU-2019:0273-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 92.0-1.2
  • MozillaThunderbird openSUSE Tumbleweed 91.1.1-1.1
  • MozillaFirefox openSUSE Leap 15.0 60.8.0-lp150.3.62.1
  • mozilla-nss openSUSE Leap 15.0 3.41.1-lp150.2.20.1
  • MozillaThunderbird Package Hub 12 60.5.1-79.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10600-1openSUSE-SU-2024:10601-1openSUSE-SU-2019:1758-1openSUSE-SU-2019:0249-1

  • firefox-esr Alpine 3.23, Alpine 3.22, Alpine 3.21 +12 more 60.5.0-r0

alpine advisories ALPINE-CVE-2018-18500

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

  • firefox Arch Linux 65.0-1

arch linux advisories AVG-862

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-2018-18500 updated cvss 9.8

Mozilla: Use-after-free parsing HTML5 stream

  • Red Hat Enterprise Linux Client (v. 7) firefox 60.5.0-2.el7, thunderbird 60.5.0-1.el7_6 Red Hat Enterprise Linux Client Optional (v. 7) firefox 60.5.0-2.el7
    fixed: vendor fix RHSA-2019:0219
  • Red Hat Enterprise Linux Desktop (v. 6) firefox 60.5.0-2.el6, thunderbird 60.5.0-1.el6_10 Red Hat Enterprise Linux Desktop Optional (v. 6) firefox 60.5.0-2.el6
    fixed: vendor fix RHSA-2019:0218
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) firefox 60.5.0-2.el7
    fixed: vendor fix RHSA-2019:0219
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) thunderbird 60.5.0-1.el7_6
    fixed: vendor fix RHSA-2019:0270
  • Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox 60.5.0-2.el6 Red Hat Enterprise Linux Server (v. 6) firefox 60.5.0-2.el6
    fixed: vendor fix RHSA-2019:0218
  • Red Hat Enterprise Linux Server (v. 7) firefox 60.5.0-2.el7
    fixed: vendor fix RHSA-2019:0219
  • Red Hat Enterprise Linux Server Optional (v. 6) firefox 60.5.0-2.el6, thunderbird 60.5.0-1.el6_10
    fixed: vendor fix RHSA-2019:0218
  • Red Hat Enterprise Linux Server Optional (v. 7) firefox 60.5.0-2.el7, thunderbird 60.5.0-1.el7_6
    fixed: vendor fix RHSA-2019:0219
show 5 more
  • Red Hat Enterprise Linux Workstation (v. 6) firefox 60.5.0-2.el6, thunderbird 60.5.0-1.el6_10
    fixed: vendor fix RHSA-2019:0218
  • Red Hat Enterprise Linux Workstation (v. 7) firefox 60.5.0-2.el7, thunderbird 60.5.0-1.el7_6
    fixed: vendor fix RHSA-2019:0219
  • Red Hat Enterprise Linux Workstation Optional (v. 6) firefox 60.5.0-2.el6
    fixed: vendor fix RHSA-2019:0218
  • Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 60.5.0-2.el7
    fixed: vendor fix RHSA-2019:0219
  • 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

12.66% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.0 9.8 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

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.