dbcve.org
FirefoxWeb browser · Mozilla

CVE-2023-4051

HIGH · 7.5 CVSS v3.1 Published 2023-08-01
Fix available
A fix is available. Upgrade to 116.0 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A website could have obscured the full screen notification by using the file open dialog. This could have led to user confusion and possible spoofing attacks. This vulnerability affects Firefox < 116, Firefox ESR < 115.2, and Thunderbird < 115.2.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A vulnerability in Firefox and Thunderbird allows a malicious website to obscure the full screen notification (which normally warns users that a site has entered full screen mode) by triggering a file open dialog on top of it. This UI spoofing issue could trick users into believing they're in a different context, facilitating phishing or spoofing attacks.

MitigationUpdate to Firefox 116+, Firefox ESR 115.2+, or Thunderbird 115.2+ to receive the vendor patch. Organizations should deploy the updated browser versions across their environment.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FirefoxWeb browser
Affected:< 116.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm Firefox is installed
    Check for Firefox installation by looking for the executable. On Windows, check Program Files\Mozilla Firefox\firefox.exe or %LOCALAPPDATA%\Mozilla Firefox\firefox.exe. On macOS, check /Applications/Firefox.app. On Linux, check /usr/lib/firefox or /opt/firefox.
    Affected if Firefox is present on the system
  2. Find the installed Firefox version
    Open Firefox, click the menu button (three horizontal lines), select Help, then About Firefox. The version number displayed is the installed version.
    Affected if version number shown is below 116.0 (for example, 115.x or earlier)
  3. Alternatively, check version from command line
    Run 'firefox --version' from command prompt or terminal. On Windows PowerShell: & 'C:\Program Files\Mozilla Firefox\firefox.exe' -v
    Affected if command output shows a version below 116.0
  4. Check if fullscreen feature is used
    This vulnerability requires a website to enter fullscreen mode and trigger a file open dialog. Determine if users in your environment commonly browse untrusted websites that could trigger these conditions.
    Affected if Users browse untrusted websites and the Firefox version is below 116.0

A user is affected if they have Mozilla Firefox installed with a version lower than 116.0 and browse websites that could exploit this UI spoofing flaw.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 116.0 or later
Fixed in 116.0
Interim mitigation

Update to Firefox 116+, Firefox ESR 115.2+, or Thunderbird 115.2+ to receive the vendor patch. Organizations should deploy the updated browser versions across their environment.

Recommended fix High confidence

Firefox 116.0, Firefox ESR 115.2, Thunderbird 115.2

  1. 1. Open Firefox and navigate to Menu > Help > About Firefox, or go to about:support in the address bar
  2. 2. Click 'Check for Updates' or wait for Firefox to automatically check
  3. 3. If an update is available, click 'Restart to Update Firefox' to download and install version 116.0 or later
  4. 4. Alternatively, visit https://www.mozilla.org/firefox/ and download Firefox 116.0 or later
  5. 5. Run the installer and complete the installation
  6. 6. Restart Firefox if not automatically prompted
Caveat Most users will not experience breaking changes; some older add-ons or extensions may need updates for compatibility

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $890
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,424.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-4051 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data