Spoofing attack in Mozilla Firefox - CVE-2020-12394

Vulnerability identifier: #VU27537

CSH Severity: Low

CVSS v4: 2.4 [CVSS:4.0/AV:P/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2020-12394

CWE-ID: CWE-451

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to perform spoofing attack.

The vulnerability exists due to a logic flaw in the location bar implementation. A local user can spoof  the current location by selecting a different origin and removing focus from the input element.

Mozilla Firefox
Arch Linux
Gentoo Linux
firefox (Ubuntu package)
firefox (Alpine package)

Install updates from vendor's website.

Mozilla Firefox - update to 76.0
firefox (Ubuntu package) - addressed in versions 76.0+build2-0ubuntu0.16.04.1, 76.0+build2-0ubuntu0.18.04.1, 76.0+build2-0ubuntu0.19.10.1, 76.0+build2-0ubuntu0.20.04.1, 76.0.1+build1-0ubuntu0.16.04.1, 76.0.1+build1-0ubuntu0.18.04.1, 76.0.1+build1-0ubuntu0.19.10.1, 76.0.1+build1-0ubuntu0.20.04.1
firefox (Alpine package) - update to 76.0-r0

• https://www.mozilla.org/en-US/security/advisories/mfsa2020-16/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1628288

• Multiple vulnerabilities in Mozilla Firefox and Firefox ESR
• Arch Linux update for firefox
• Ubuntu update for Firefox
• Ubuntu regressions update for Firefox
• Gentoo update for Mozilla Firefox
• Spoofing attack in firefox (Alpine package)