CVE-2020-12423

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-07-09 · updated 2026-06-17
Weakness: CWE-427

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.

Affected products

Mozilla Firefox: before 78.0 — fixed in 78.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 78.0. Check the vendor advisory for mitigations.

References

http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00027.html
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00049.html
https://bugzilla.mozilla.org/show_bug.cgi?id=1642400
https://www.mozilla.org/security/advisories/mfsa2020-24/
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00027.html
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00049.html
https://bugzilla.mozilla.org/show_bug.cgi?id=1642400
https://www.mozilla.org/security/advisories/mfsa2020-24/

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