CVE-2020-6810Public exploitNetwork attack vector

Credential theft via fullscreen popup notification spoofing

Published Mar 25, 2020 · Updated Aug 4, 2024

UI spoofing in Mozilla Firefox before 74 allows remote attackers to obscure the fullscreen origin warning with a previously opened popup. While a site is in DOM fullscreen, Firefox permits that popup to be focused above the security notification instead of leaving fullscreen, hiding the trusted origin indicator. Exploitation requires user interaction with crafted content and spoofed browser chrome; the resulting deception can capture credentials or misattribute the page origin.

CVSS severity4.3
Medium
EPSS probability1.00%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

UI spoofing in Mozilla Firefox before 74 allows remote attackers to obscure the fullscreen origin warning with a previously opened popup. While a site is in DOM fullscreen, Firefox permits that popup to be focused above the security notification instead of leaving fullscreen, hiding the trusted origin indicator. Exploitation requires user interaction with crafted content and spoofed browser chrome; the resulting deception can capture credentials or misattribute the page origin.

The record

CVE
CVE-2020-6810
Published
Mar 25, 2020
Updated
Aug 4, 2024
Vendor
Mozilla
Product
Firefox
Classifications
CWE-290, T1036
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 25, 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

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Is a vulnerable build present?

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

  1. Affected versionversion=unspecified <74

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <74

Published CVSS scores

4.3NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
4.3NIST National Vulnerability DatabaseAV:N/AC:M/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-290Authentication Bypass by Spoofing
T1036Masquerading

Public exploit references

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

Technologies

Your stack

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Your stack

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