high 8.8

CVE-2020-12417 json

Due to confusion about ValueTags on JavaScript Objects, an object may pass through the type barrier, resulting in memory corruption and a p…

published 2020-07-09 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-4729

cvss: 8.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 2.7%; EPSS 2.7% chance of exploitation in 30 days, percentile 85%
public exploits: 0; none known

Due to confusion about ValueTags on JavaScript Objects, an object may pass through the type barrier, resulting in memory corruption and a potentially exploitable crash. *Note: this issue only affects Firefox on ARM64 platforms.* 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-2020-12417

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-2020-12417

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 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
thunderbird RHEL 8.0 E4S 68.10.0-1.el8_0
thunderbird RHEL 8.1 EUS 68.10.0-1.el8_1
firefox RHEL 8.1 EUS 68.10.0-1.el8_1
firefox RHEL 8.0 E4S 68.10.0-1.el8_0

red hat advisories RHSA-2020:3046 RHSA-2020:3038 RHSA-2020:2907 RHSA-2020:2906 RHSA-2020:2828 RHSA-2020:2826

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-2020-12417

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-2020-12417 updated 2026-11-04 cvss 8.8

Mozilla: Memory corruption due to missing sign-extension for ValueTags on ARM64

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 Red Hat Enterprise Linux Server (v. 7) firefox 68.10.0-1.el7_8 Red Hat Enterprise Linux Server Optional (v. 7) firefox 68.10.0-1.el7_8, thunderbird 68.10.0-1.el7_8 Red Hat Enterprise Linux Workstation (v. 7) firefox 68.10.0-1.el7_8, thunderbird 68.10.0-1.el7_8 Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 68.10.0-1.el7_8
fixed: vendor fix RHSA-2020:2827
Red Hat Enterprise Linux 5 firefox, thunderbird Red Hat Enterprise Linux 6 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

2.68% chance of exploitation in the next 30 days, higher than 85% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

bugzilla.mozilla.org https://bugzilla.mozilla.org/show_bug.cgi?id=1640737 referenced PoC, tagged "exploit" by a source, unverified

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
NVD	2.0	9.3	AV:N/AC:M/Au:N/C:C/I:C/A:C

Affected products

Mozilla Firefox ESR
Mozilla Firefox
Mozilla Thunderbird

Classification

Weakness

CWE-617 Reachable Assertion
CWE-681 Incorrect Conversion between Numeric Types
CWE-787 Out-of-bounds Write

References

bugzilla.mozilla.org /show_bug.cgi?id=1640737
exploit, issue-tracking, vendor-advisory
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

Sources

CVE List CVE-2020-12417
NVD CVE-2020-12417

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.

Summary