CVE-2020-12423

Name: CVE-2020-12423
Creator: NVD / NIST
Published: 2020-07-09T15:15:12.193+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.8/10EPSS 0.41%

Last modified Jun 17, 2026

CVE-2020-12423 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. When the Windows DLL "webauthn.dll" was missing from the Operating System, and a malicious one was placed in a folder in the user's %PATH%, Firefox may have loaded the DLL, leading to arbitrary code execution. *Note: This issue only affects the Windows operating system; other operating systems are unaffected.* This vulnerability affects Firefox < 78.. EPSS estimates a 0.41% chance of exploitation in the next 30 days.

Description

When the Windows DLL "webauthn.dll" was missing from the Operating System, and a malicious one was placed in a folder in the user's %PATH%, Firefox may have loaded the DLL, leading to arbitrary code execution. *Note: This issue only affects the Windows operating system; other operating systems are unaffected.* This vulnerability affects Firefox < 78.

Metrics

CVSS 3.1

7.8/10

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

EPSS Probability

0.41%

33.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-427

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 78.0

References

http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00027.htmlBroken Link
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00049.htmlBroken Link
https://bugzilla.mozilla.org/show_bug.cgi?id=1642400Issue Tracking, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-24/Vendor Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00027.htmlBroken Link
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00049.htmlBroken Link
https://bugzilla.mozilla.org/show_bug.cgi?id=1642400Issue Tracking, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2020-24/Vendor Advisory

Timeline

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

Frequently Asked Questions

What is CVE-2020-12423?

How severe is CVE-2020-12423?

CVE-2020-12423 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.41% probability of exploitation in the next 30 days.

How do I fix CVE-2020-12423?

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-2020-12423?

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

Scan your code now

Source: NVD / NIST