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Fencer Intel
medium 4.3

CVE-2020-12397 json

By encoding Unicode whitespace characters within the From email header, an attacker can spoof the sender email address that Thunderbird dis…

published 6y ago modified 4mo ago also EUVD-2020-4709

cvss
4.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 49%
public exploits
0
none known

Summary

By encoding Unicode whitespace characters within the From email header, an attacker can spoof the sender email address that Thunderbird displays. This vulnerability affects Thunderbird < 68.8.0.

Patch / fix

  • Mozilla Thunderbird 68.8.0
  • thunderbird Debian 14, Debian 13, Debian 12 1:68.8.0-1

debian advisories DEBIAN-CVE-2020-12397

  • thunderbird Ubuntu 16.04 LTS 1:68.8.0+build2-0ubuntu0.16.04.2
  • thunderbird Ubuntu 18.04 LTS 1:68.8.0+build2-0ubuntu0.18.04.2
  • thunderbird Ubuntu 20.04 LTS 1:68.8.0+build2-0ubuntu0.20.04.2

ubuntu advisories UBUNTU-CVE-2020-12397

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 68.8.0-1.el7_8
  • thunderbird RHEL 8 68.8.0-1.el8_2
  • thunderbird RHEL 6 68.8.0-1.el6_10
  • thunderbird RHEL 8.1 EUS 68.8.0-1.el8_1
  • thunderbird RHEL 8.0 E4S 68.8.0-1.el8_0

red hat advisories RHSA-2020:2050RHSA-2020:2046RHSA-2020:2049RHSA-2020:2047RHSA-2020:2048

  • MozillaThunderbird SLE Workstation Extension 15 SP1 68.8.0-3.80.2

suse advisories SUSE-SU-2020:1225-1

  • MozillaThunderbird openSUSE Tumbleweed 91.1.1-1.1
  • MozillaThunderbird openSUSE Leap 15.1 68.8.0-lp151.2.38.2

opensuse advisories openSUSE-SU-2024:10601-1openSUSE-SU-2020:0643-1

  • thunderbird Alpine 3.23, Alpine 3.22, Alpine 3.21 +5 more 68.8.0-r0

alpine advisories ALPINE-CVE-2020-12397

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

  • thunderbird Arch Linux 68.8.0-1

arch linux advisories AVG-1155

Is CVE-2020-12397 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.

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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-2020-12397 updated cvss 4.3

Mozilla: Sender Email Address Spoofing using encoded Unicode characters

  • Red Hat Enterprise Linux 5 thunderbird
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) thunderbird 68.8.0-1.el8_2
    fixed: vendor fix RHSA-2020:2046
  • Red Hat Enterprise Linux AppStream E4S (v. 8.0) thunderbird 68.8.0-1.el8_0
    fixed: vendor fix RHSA-2020:2048
  • Red Hat Enterprise Linux AppStream EUS (v. 8.1) thunderbird 68.8.0-1.el8_1
    fixed: vendor fix RHSA-2020:2047
  • Red Hat Enterprise Linux Client (v. 7) thunderbird 68.8.0-1.el7_8
    fixed: vendor fix RHSA-2020:2050
  • Red Hat Enterprise Linux Desktop (v. 6) thunderbird 68.8.0-1.el6_10 Red Hat Enterprise Linux Server Optional (v. 6) thunderbird 68.8.0-1.el6_10
    fixed: vendor fix RHSA-2020:2049
  • Red Hat Enterprise Linux Server Optional (v. 7) thunderbird 68.8.0-1.el7_8
    fixed: vendor fix RHSA-2020:2050
  • Red Hat Enterprise Linux Workstation (v. 6) thunderbird 68.8.0-1.el6_10
    fixed: vendor fix RHSA-2020:2049
show 1 more
  • Red Hat Enterprise Linux Workstation (v. 7) thunderbird 68.8.0-1.el7_8
    fixed: vendor fix RHSA-2020:2050

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

0.61% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

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

Affected products

  • Mozilla Thunderbird

Classification

Weakness

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.