CVE-2023-4051Network attack vector

UI spoofing via file-picker warning overlap

Published Aug 1, 2023 · Updated Dec 18, 2025

UI spoofing in Mozilla Firefox before 116, Firefox ESR before 115.2, and Thunderbird before 115.2 allows remote attackers to spoof browser chrome. The fullscreen-warning state remains active while a website opens the operating-system file picker, allowing that dialog to cover the site-origin notice. Exploitation requires fullscreen and file-picker interaction; the resulting risk is deceptive page chrome and user confusion, not reported code execution or data access.

CVSS severity7.5
High
EPSS probability0.66%
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 116, Firefox ESR before 115.2, and Thunderbird before 115.2 allows remote attackers to spoof browser chrome. The fullscreen-warning state remains active while a website opens the operating-system file picker, allowing that dialog to cover the site-origin notice. Exploitation requires fullscreen and file-picker interaction; the resulting risk is deceptive page chrome and user confusion, not reported code execution or data access.

The record

CVE
CVE-2023-4051
Published
Aug 1, 2023
Updated
Dec 18, 2025
Vendor
Mozilla
Product
Firefox
Classifications
T1036
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 1, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 18, 2025Record 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=0 <116
  2. Affected versionversion=unspecified <116

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=0 <116; version=unspecified <116
Mozilla · Thunderbirdversion=0 <115.2; version=unspecified <115.2
Mozilla · Firefox ESRversion=0 <115.2; version=unspecified <115.2

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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 exploitUnconfirmed

Weakness, pattern, technique

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

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Your stack

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