medium 6.5

CVE-2020-12418 json

Manipulating individual parts of a URL object could have caused an out-of-bounds read, leaking process memory to malicious JavaScript.

published 2020-07-09 6y ago modified 2026-06-17 4mo ago also EUVD-2020-4730

cvss: 6.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 3.0%; EPSS 3.0% chance of exploitation in 30 days, percentile 87%
public exploits: 0; none known

Manipulating individual parts of a URL object could have caused an out-of-bounds read, leaking process memory to malicious JavaScript. This vulnerability affects Firefox ESR < 68.10, Firefox < 78, and Thunderbird < 68.10.0.

Patch / fix

fixed in 3 distros 6

Mozilla Firefox ESR 68.10
Mozilla Firefox 78
Mozilla Thunderbird 68.10.0

debian ubuntu red hat suse opensuse alpine

firefox-esr Debian 14, Debian 13, Debian 12 68.10.0esr-1
thunderbird Debian 14, Debian 13, Debian 12 1:68.10.0-1

debian advisories DEBIAN-CVE-2020-12418

firefox Ubuntu 16.04 LTS 78.0.1+build1-0ubuntu0.16.04.1
firefox Ubuntu 18.04 LTS 78.0.1+build1-0ubuntu0.18.04.1
firefox Ubuntu 20.04 LTS 78.0.1+build1-0ubuntu0.20.04.1
thunderbird Ubuntu 16.04 LTS 1:68.10.0+build1-0ubuntu0.16.04.1
thunderbird Ubuntu 18.04 LTS 1:68.10.0+build1-0ubuntu0.18.04.1
thunderbird Ubuntu 20.04 LTS 1:68.10.0+build1-0ubuntu0.20.04.1

ubuntu advisories UBUNTU-CVE-2020-12418

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 68.10.0-1.el8_2
thunderbird RHEL 6 68.10.0-1.el6_10
thunderbird RHEL 7 68.10.0-1.el7_8
firefox RHEL 8 68.10.0-1.el8_2
firefox RHEL 7 68.10.0-1.el7_8
firefox RHEL 6 68.10.0-1.el6_10
thunderbird RHEL 8.0 E4S 68.10.0-1.el8_0
thunderbird RHEL 8.1 EUS 68.10.0-1.el8_1

red hat advisories RHSA-2020:3046 RHSA-2020:3038 RHSA-2020:2966 RHSA-2020:2907 RHSA-2020:2906 RHSA-2020:2828

MozillaThunderbird SLE Workstation Extension 15 SP2, SLE Workstation Extension 15 SP1 68.10.0-3.88.1
MozillaFirefox SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +15 more 78.0.1-112.3.1
MozillaFirefox-branding-SLE SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +14 more 78-35.3.1
MozillaFirefox SLE Module for Desktop Applications 15 SP2, SLE Module for Desktop Applications 15 SP1 78.0.1-3.94.2
MozillaFirefox-branding-SLE SLE Module for Desktop Applications 15 SP2, SLE Module for Desktop Applications 15 SP1 78-4.14.1
MozillaFirefox SLES 11 SP4-LTSS 78.0.1-78.80.2
MozillaFirefox-branding-SLED SLES 11 SP4-LTSS 78-21.12.1

suse advisories SUSE-SU-2020:1900-1 SUSE-SU-2020:1899-1 SUSE-SU-2020:1898-1 SUSE-SU-2020:14421-1

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 15.1 78.0.1-lp151.2.53.1
MozillaFirefox openSUSE Leap 15.2 78.0.1-lp152.2.5.1
MozillaThunderbird openSUSE Leap 15.2 68.10.0-lp152.2.4.1
MozillaThunderbird openSUSE Leap 15.1 68.10.0-lp151.2.44.2

opensuse advisories openSUSE-SU-2024:14572-1 openSUSE-SU-2024:10600-1 openSUSE-SU-2024:10601-1 openSUSE-SU-2020:1017-1 openSUSE-SU-2020:0983-1 openSUSE-SU-2020:0982-1

firefox Alpine 3.23, Alpine 3.22, Alpine 3.21 +9 more 78.0-r0
mozjs68 Alpine 3.12 68.10.0-r0
librewolf Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 78.0-r0
firefox-esr Alpine 3.23, Alpine 3.22, Alpine 3.21 +10 more 68.10.0-r0
thunderbird Alpine 3.23, Alpine 3.22, Alpine 3.21 +5 more 68.10.0-r0

alpine advisories ALPINE-CVE-2020-12418

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

Is CVE-2020-12418 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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-2020-12418 updated 2026-11-04 cvss 6.5

Mozilla: Information disclosure due to manipulated URL object

Red Hat Enterprise Linux 5 firefox, thunderbird
affected: no fix planned “Out of support scope”
Red Hat Enterprise Linux AppStream (v. 8) firefox 68.10.0-1.el8_2, thunderbird 68.10.0-1.el8_2
fixed: vendor fix RHSA-2020:2828
Red Hat Enterprise Linux AppStream E4S (v. 8.0) firefox 68.10.0-1.el8_0, thunderbird 68.10.0-1.el8_0
fixed: vendor fix RHSA-2020:2825
Red Hat Enterprise Linux AppStream EUS (v. 8.1) firefox 68.10.0-1.el8_1, thunderbird 68.10.0-1.el8_1
fixed: vendor fix RHSA-2020:2826
Red Hat Enterprise Linux Client (v. 7) firefox 68.10.0-1.el7_8, thunderbird 68.10.0-1.el7_8 Red Hat Enterprise Linux Client Optional (v. 7) firefox 68.10.0-1.el7_8
fixed: vendor fix RHSA-2020:2827
Red Hat Enterprise Linux Desktop (v. 6) firefox 68.10.0-1.el6_10, thunderbird 68.10.0-1.el6_10 Red Hat Enterprise Linux Desktop Optional (v. 6) firefox 68.10.0-1.el6_10 Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox 68.10.0-1.el6_10 Red Hat Enterprise Linux Server (v. 6) firefox 68.10.0-1.el6_10
fixed: vendor fix RHSA-2020:2824
Red Hat Enterprise Linux Server (v. 7) firefox 68.10.0-1.el7_8
fixed: vendor fix RHSA-2020:2827
Red Hat Enterprise Linux Server Optional (v. 6) firefox 68.10.0-1.el6_10, thunderbird 68.10.0-1.el6_10
fixed: vendor fix RHSA-2020:2824

show 5 more

Red Hat Enterprise Linux Server Optional (v. 7) firefox 68.10.0-1.el7_8, thunderbird 68.10.0-1.el7_8
fixed: vendor fix RHSA-2020:2827
Red Hat Enterprise Linux Workstation (v. 6) firefox 68.10.0-1.el6_10, thunderbird 68.10.0-1.el6_10
fixed: vendor fix RHSA-2020:2824
Red Hat Enterprise Linux Workstation (v. 7) firefox 68.10.0-1.el7_8, thunderbird 68.10.0-1.el7_8
fixed: vendor fix RHSA-2020:2827
Red Hat Enterprise Linux Workstation Optional (v. 6) firefox 68.10.0-1.el6_10
fixed: vendor fix RHSA-2020:2824
Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 68.10.0-1.el7_8
fixed: vendor fix RHSA-2020:2827

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

3.03% chance of exploitation in the next 30 days, higher than 87% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
NVD	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
NVD	2.0	4.3	AV:N/AC:M/Au:N/C:P/I:N/A:N

Affected products

Mozilla Firefox ESR
Mozilla Firefox
Mozilla Thunderbird

Classification

Weakness

CWE-125 Out-of-bounds Read

References

lists.opensuse.org /opensuse-security-announce/2020-07/msg00023.html
vendor-advisory, mailing-list, third-party-advisory
lists.opensuse.org /opensuse-security-announce/2020-07/msg00026.html
vendor-advisory, mailing-list, third-party-advisory
lists.opensuse.org /opensuse-security-announce/2020-07/msg00027.html
vendor-advisory, mailing-list, third-party-advisory
lists.opensuse.org /opensuse-security-announce/2020-07/msg00049.html
vendor-advisory, mailing-list, third-party-advisory
usn.ubuntu.com /4421-1/
vendor-advisory, third-party-advisory
security.gentoo.org /glsa/202007-09
vendor-advisory, third-party-advisory
security.gentoo.org /glsa/202007-10
vendor-advisory, third-party-advisory
mozilla.org /security/advisories/mfsa2020-24/
vendor-advisory
mozilla.org /security/advisories/mfsa2020-26/
vendor-advisory
mozilla.org /security/advisories/mfsa2020-25/
vendor-advisory
bugzilla.mozilla.org /show_bug.cgi?id=1641303
issue-tracking, permissions-required, vendor-advisory

Sources

CVE List CVE-2020-12418
NVD CVE-2020-12418

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.

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