FirefoxWeb browser · Mozilla
CVE-2017-7770
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 mechanism where when a new tab is loaded through JavaScript events, if fullscreen mode is then entered, the addressbar will not be rendered. This would allow a malicious site to displayed a spoofed addressbar, showing the location of an arbitrary website instead of the one loaded. Note: this issue only affects Firefox for Android. Desktop Firefox is unaffected. This vulnerability affects Firefox < 54.
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 confidenceIn Firefox for Android versions before 54, when JavaScript loads a new tab and fullscreen mode is subsequently entered, the browser fails to render the address bar. This enables a malicious website to display a fake address bar showing an arbitrary URL instead of the legitimate site location.
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
< 54.0CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.0/AV:N/AC:H/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 checksWork through these to decide whether this CVE applies to you.
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Identify if Firefox for Android is installedCheck the device's installed apps for Mozilla Firefox specifically for Android (not Firefox Desktop, Firefox Focus, or other Mozilla products)Affected if The app is Firefox for Android on the device
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Check the Firefox for Android version numberOpen the app, tap the three-dot menu, go to Help > About Firefox, or check the app version in device Settings > Apps > FirefoxAffected if The displayed version number is less than 54.0 (for example, 53.x, 52.x, etc.)
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Verify the fullscreen tab loading scenarioUse JavaScript in a webpage to programmatically load a new tab (via window.open or similar) and then trigger fullscreen mode (via requestFullscreen API)Affected if The address bar becomes invisible or fails to render after this sequence, allowing a fake URL to be displayed in its place
You are affected if Firefox for Android is installed with a version lower than 54.0 and you browse the web in fullscreen mode after JavaScript opens a new tab.
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.
From vendor data54.0
Upgrade Firefox for Android to version 54 or later. Users should be advised to keep their mobile browsers updated through official app stores or enterprise mobility management tools.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 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 $1,456.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-7770 — 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-2017-7770 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
- No spam, self-promotion, credentials, or personal data