FirefoxWeb browser · Mozilla
CVE-2025-55030
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 · uneditedFirefox for iOS would not respect a Content-Disposition header of type Attachment and would incorrectly display the content inline rather than downloading, potentially allowing for XSS 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 · high confidenceFirefox for iOS failed to honor the Content-Disposition: attachment HTTP header, causing the browser to render content inline rather than triggering a download. This behavior could enable cross-site scripting (XSS) attacks by allowing malicious content to be executed within the browser context instead of being safely downloaded.
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
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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 the installed browser productCheck if the device has Firefox for iOS installed. On iOS, navigate to Settings > Firefox (if installed) or check the app in the iOS App Store. Confirm this is Firefox for iOS specifically, not Firefox Focus or other Mozilla browsers.Affected if Firefox for iOS is the installed product
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Determine the installed version numberOpen Firefox for iOS, tap the menu button (hamburger icon), scroll down and tap Help, then tap About Firefox to view the version number. Alternatively, check the version in the App Store app listing.Affected if The version displayed is visible
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Compare version against affected rangeTake the installed version number (e.g., 141.5) and compare it numerically to 142.0. Any version lower than 142.0 falls within the affected range.Affected if The installed version is less than 142.0
The environment is affected if Firefox for iOS is installed and the installed version is below 142.0.
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 receive the security fix that properly handles Content-Disposition headers.
Firefox for iOS 142.0
- Open the App Store on your iOS device
- Search for "Firefox" or locate it in your purchased apps
- Tap the "Update" button next to Firefox to update to the latest version
- Alternatively, enable automatic updates by going to Settings > App Store > Automatic Downloads and enabling Updates
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 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 $1,696.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-55030 — 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-2025-55030 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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- 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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