FirefoxWeb browser · Mozilla
CVE-2025-55029
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 · uneditedMalicious scripts could bypass the popup blocker to spam new tabs, potentially resulting in denial of service attacks. This vulnerability was fixed in Firefox for iOS 142.
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 · moderate confidenceFirefox for iOS had a vulnerability where malicious JavaScript could bypass the popup blocker and spawn excessive new tabs, potentially causing the browser to become unresponsive or crash (denial of service).
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
< 142.0CVSS 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
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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 Firefox for iOS versionOpen the App Store app, tap your profile icon, scroll to Firefox for iOS, and view the version number shown. Alternatively, open Firefox, go to Settings > About Firefox to display the version.Affected if The displayed version is any version number less than 142.0 (for example, 141.0, 140.5, etc.)
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Confirm the app is the genuine Mozilla FirefoxVerify the app was downloaded from the official Apple App Store and is published by Mozilla. Malicious third-party browsers may have different version schemes.Affected if The app is a legitimate Firefox for iOS copy from the official App Store.
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Understand the exploitation conditionThis vulnerability is triggered when a webpage contains malicious JavaScript that attempts to open multiple popups or new tabs in rapid succession. The flaw allows the popup blocker to be bypassed.Affected if The browser is used to browse untrusted websites and the installed version is below 142.0.
A user is affected if Firefox for iOS version is below 142.0 and the browser is used to visit websites containing malicious JavaScript designed to exploit the popup blocker bypass.
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 · scoped142.0
Update Firefox for iOS to version 142 or later to obtain the patched version.
Firefox for iOS 142.0
- Open the App Store on your iOS device
- Search for "Firefox" or locate it in your installed apps
- Tap on the Firefox app to open its App Store page
- If an update is available, tap "Update" to download and install Firefox 142.0 or later
- Alternatively, enable automatic updates by going to Settings > App Store > Enable automatic downloads for apps
- After updating, verify the version by opening Firefox, tapping the menu (three lines), selecting Settings, and scrolling to the bottom to confirm version 142.0 or higher is installed
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 h
- Implementation0.5 h
- Testing0.5 h
- Review / QA0.5 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-2025-55029 — 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-2025-55029 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