FirefoxWeb browser · Mozilla
CVE-2023-37204
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 · uneditedA website could have obscured the fullscreen notification by using an option element by introducing lag via an expensive computational function. This could have led to user confusion and possible spoofing attacks. This vulnerability affects Firefox < 115.
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 confidenceThis is a UI spoofing vulnerability in Firefox where a malicious website can obscure the browser's fullscreen notification by using an <option> element combined with expensive computational functions to introduce lag. This prevents users from knowing they've entered fullscreen mode, enabling potential spoofing attacks where a site could impersonate another site's content.
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
< 115.0CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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 checksWork through these to decide whether this CVE applies to you.
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Check your Firefox version numberOpen Firefox and navigate to Help > About Firefox, or type 'about:support' in the address bar. Locate the version number displayed.Affected if The displayed version is less than 115.0 (for example, 114.x, 114.0.1, etc.)
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Confirm fullscreen API availabilityThis vulnerability affects the fullscreen notification feature. The fullscreen API is a standard browser feature enabled by default in Firefox.Affected if Fullscreen mode functionality is available and can be triggered (for example, by a website calling the requestFullscreen() method)
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Verify browser is not a patched variantConfirm you are using the standard Mozilla Firefox browser and not an older, unpatched build or a forked version that may not have received the fix.Affected if You are using a standard Firefox build that has not been updated to version 115.0 or later
You are affected if your installed Firefox version is below 115.0 and you use the browser's fullscreen functionality, as the fullscreen notification can be obscured by the described attack technique.
Generated from the published advisory. Verify against your own configuration.
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 · scoped115.0
Upgrade Firefox to version 115 or later. Users should ensure their browser is updated to receive the fix for this vulnerability.
Firefox 115.0 or later
- 1. Save any open work in Firefox
- 2. Close the Firefox browser completely
- 3. Download Firefox version 115.0 or later from the official Mozilla website (www.mozilla.org)
- 4. Run the installer and follow the prompts to install the updated version
- 5. Restart Firefox and verify the version by navigating to Help > About Firefox
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-37204 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-37204 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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
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