CVE-2020-12397

Name: CVE-2020-12397
Creator: NVD / NIST
Published: 2020-05-22T19:15:15.58+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.3/10EPSS 0.60%

Last modified Jun 17, 2026

CVE-2020-12397 is a medium-severity vulnerability rated 4.3/10 on the CVSS scale. 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.. EPSS estimates a 0.60% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

4.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

EPSS Probability

0.60%

44.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-346

Affected Software

Vendor	Product	Versions
Mozilla	Thunderbird	< 68.8.0
Canonical	Ubuntu Linux	16.04
Canonical	Ubuntu Linux	18.04
Canonical	Ubuntu Linux	19.10
Canonical	Ubuntu Linux	20.04

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1617370Issue Tracking, Patch, Vendor Advisory
https://security.gentoo.org/glsa/202005-03Third Party Advisory
https://usn.ubuntu.com/4373-1/Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2020-18/Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1617370Issue Tracking, Patch, Vendor Advisory
https://security.gentoo.org/glsa/202005-03Third Party Advisory
https://usn.ubuntu.com/4373-1/Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2020-18/Vendor Advisory

Timeline

Published: May 22, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-12397?

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.

How severe is CVE-2020-12397?

CVE-2020-12397 has a CVSS score of 4.3/10 (MEDIUM severity). The EPSS model estimates a 0.60% probability of exploitation in the next 30 days.

How do I fix CVE-2020-12397?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-12397?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST