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Fencer Vulns
high 8.8

CVE-2020-12422 json

In non-standard configurations, a JPEG image created by JavaScript could have caused an internal variable to overflow, resulting in an out…

published 2020-07-09 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-4734

cvss
8.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.9%
EPSS 1.9% chance of exploitation in 30 days, percentile 80%
public exploits
0
none known

Summary

In non-standard configurations, a JPEG image created by JavaScript could have caused an internal variable to overflow, resulting in an out of bounds write, memory corruption, and a potentially exploitable crash. This vulnerability affects Firefox < 78.

Patch / fix

  • Mozilla Firefox 78
  • 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 18.04 LTS 1:78.8.1+build1-0ubuntu0.18.04.1
  • thunderbird Ubuntu 20.04 LTS 1:78.7.1+build1-0ubuntu0.20.04.1

ubuntu advisories UBUNTU-CVE-2020-12422

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

  • firefox RHEL 7 78.3.0-1.el7_9
  • firefox RHEL 8 78.2.0-2.el8_2
  • firefox RHEL 8.0 E4S 78.2.0-3.el8_0
  • firefox RHEL 8.1 EUS 78.2.0-3.el8_1

red hat advisories RHSA-2020:4080RHSA-2020:3555RHSA-2020:3559RHSA-2020:3557

  • 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-2020:1899-1SUSE-SU-2020:1898-1SUSE-SU-2020:14421-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 92.0-1.2
  • MozillaFirefox openSUSE Leap 15.1 78.0.1-lp151.2.53.1
  • MozillaFirefox openSUSE Leap 15.2 78.0.1-lp152.2.5.1

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

  • firefox Alpine 3.23, Alpine 3.22, Alpine 3.21 +9 more 78.0-r0
  • librewolf Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 78.0-r0

alpine advisories ALPINE-CVE-2020-12422

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-2020-12422 updated cvss 8.8

Mozilla: Integer overflow in nsJPEGEncoder::emptyOutputBuffer

  • Red Hat Enterprise Linux 5 firefox Red Hat Enterprise Linux 6 firefox
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) firefox 78.2.0-2.el8_2
    fixed: vendor fix RHSA-2020:3557
  • Red Hat Enterprise Linux AppStream E4S (v. 8.0) firefox 78.2.0-3.el8_0
    fixed: vendor fix RHSA-2020:3555
  • Red Hat Enterprise Linux AppStream EUS (v. 8.1) firefox 78.2.0-3.el8_1
    fixed: vendor fix RHSA-2020:3559
  • Red Hat Enterprise Linux Client (v. 7) firefox 78.3.0-1.el7_9 Red Hat Enterprise Linux Client Optional (v. 7) firefox 78.3.0-1.el7_9 Red Hat Enterprise Linux Server (v. 7) firefox 78.3.0-1.el7_9 Red Hat Enterprise Linux Server Optional (v. 7) firefox 78.3.0-1.el7_9 Red Hat Enterprise Linux Workstation (v. 7) firefox 78.3.0-1.el7_9 Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 78.3.0-1.el7_9
    fixed: vendor fix RHSA-2020:4080

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

1.94% chance of exploitation in the next 30 days, higher than 80% 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
NVD 2.0 7.6 AV:N/AC:H/Au:N/C:C/I:C/A:C

Affected products

  • 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.