FirefoxWeb browser · Mozilla
CVE-2025-27426
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 websites utilizing a server-side redirect to an internal error page could result in a spoofed website URL. This vulnerability was fixed in Firefox for iOS 136.
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 confidenceA URL spoofing vulnerability in Firefox for iOS where malicious websites could exploit server-side redirects to internal error pages to disguise the actual URL being visited, potentially tricking users into believing they're on a legitimate site.
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
< 136.0CVSS 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
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/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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Confirm Firefox for iOS is installedCheck if the Firefox app is present on the iOS device. Go to the home screen and search for 'Firefox' or check the app library.Affected if Firefox for iOS is not found on the device - this CVE does not apply
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Identify the installed Firefox for iOS versionOpen Firefox for iOS, tap the menu (hamburger icon), scroll down to Settings, tap Settings, then look for 'Firefox' at the top which displays the version number (e.g., 135.0, 135.1, etc.).Affected if The displayed version number is less than 136.0 (such as 135.x, 134.x, or earlier)
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Verify version via iOS SettingsOpen the iOS Settings app, scroll to 'Firefox' in the list of installed apps, tap it, and check the version number displayed.Affected if The version shown is 135.x or lower - the vulnerable version is installed
A user is affected if Firefox for iOS is installed and the version is below 136.0, as the URL spoofing vulnerability exists in versions prior to 136.
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 · scoped136.0
Upgrade to Firefox for iOS version 136 or later to obtain the fix for this URL spoofing vulnerability.
Firefox for iOS 136.0
- Open the App Store on your iOS device
- Tap on your profile icon in the top right corner
- Scroll down to see available updates
- Find Firefox for iOS in the list of apps with pending updates
- Tap Update next to Firefox for iOS
- Wait for the update to download and install
- Alternatively, search for Firefox in the App Store and tap Update if an update is available
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-2025-27426 — 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-2025-27426 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