CVE-2020-12405

Name: CVE-2020-12405
Creator: NVD / NIST
Published: 2020-07-09T15:15:10.943+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 1.35%

Last modified Jun 17, 2026

CVE-2020-12405 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. When browsing a malicious page, a race condition in our SharedWorkerService could occur and lead to a potentially exploitable crash. This vulnerability affects Thunderbird < 68.9.0, Firefox < 77, and Firefox ESR < 68.9.. EPSS estimates a 1.35% chance of exploitation in the next 30 days.

Description

When browsing a malicious page, a race condition in our SharedWorkerService could occur and lead to a potentially exploitable crash. This vulnerability affects Thunderbird < 68.9.0, Firefox < 77, and Firefox ESR < 68.9.

Metrics

CVSS 3.1

5.3/10

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

EPSS Probability

1.35%

68.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 77.0
Mozilla	Firefox Esr	< 68.9.0
Mozilla	Thunderbird	< 68.9.0
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=1631618Exploit, Issue Tracking, Vendor Advisory
https://usn.ubuntu.com/4421-1/Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2020-20/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-21/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-22/Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1631618Exploit, Issue Tracking, Vendor Advisory
https://usn.ubuntu.com/4421-1/Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2020-20/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-21/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-22/Vendor Advisory

Timeline

Published: Jul 9, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-12405?

How severe is CVE-2020-12405?

CVE-2020-12405 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 1.35% probability of exploitation in the next 30 days.

How do I fix CVE-2020-12405?

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-2020-12405?

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

Scan your code now

Source: NVD / NIST