CVE-2020-12394

Location spoofing via stale security indicators

Published May 26, 2020 · Updated Aug 4, 2024

URL spoofing in Mozilla Firefox before 76 allows local users to misrepresent the current site through the location bar. The Address Bar code fails to invalidate pageproxystate when a Top Site is keyboard-selected, so a canceled selection retains the chosen URL alongside the prior page's lock and permission indicators. Local browser access and location-bar interaction are required; the display can make one origin appear to carry another origin's trusted security state.

CVSS severity3.3
Low
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

URL spoofing in Mozilla Firefox before 76 allows local users to misrepresent the current site through the location bar. The Address Bar code fails to invalidate pageproxystate when a Top Site is keyboard-selected, so a canceled selection retains the chosen URL alongside the prior page's lock and permission indicators. Local browser access and location-bar interaction are required; the display can make one origin appear to carry another origin's trusted security state.

The record

CVE
CVE-2020-12394
Published
May 26, 2020
Updated
Aug 4, 2024
Vendor
Mozilla
Product
Firefox
Classifications
CWE-451, T1036
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 26, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <76

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <76

Published CVSS scores

3.3NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
2.1NVDAV:L/AC:L/Au:N/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-451User Interface (UI) Misrepresentation of Critical Information
T1036Masquerading

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo