FocusApplication · Mozilla

CVE-2026-11799

HIGH · 7.5 CVSS v3.1 Published 2026-06-09
Fix available
A fix is available. Upgrade to 151.3.1 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
UXSS in Focus for iOS / Klar Webkit navigation. This vulnerability was fixed in Focus for iOS 151.3.1 and Klar for iOS 151.3.1.

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 confidence

A Universal Cross-Site Scripting (UXSS) vulnerability in Focus for iOS and Klar for iOS browsers affecting WebKit navigation. This type of vulnerability allows an attacker to execute malicious scripts in the context of any website, bypassing the same-origin policy.

MitigationUpdate Focus for iOS and Klar for iOS to version 151.3.1 or later to remediate this vulnerability.

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
FocusApplication
Affected:< 151.3.1
KlarApplication
Affected:< 151.3.1

CVSS 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
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed browser apps
    Check the iOS device for Mozilla Focus or Mozilla Klar applications installed from the App Store
    Affected if Either Mozilla Focus or Mozilla Klar is present on the device
  2. Check Mozilla Focus version
    Open the App Store app, go to Profile > Purchased, find Mozilla Focus, and view the version number. Alternatively, check within the Focus app settings under About or Help sections if available
    Affected if The displayed version number is less than 151.3.1
  3. Check Mozilla Klar version
    Open the App Store app, go to Profile > Purchased, find Mozilla Klar, and view the version number. Alternatively, check within the Klar app settings under About or Help sections if available
    Affected if The displayed version number is less than 151.3.1
  4. Confirm vulnerability applicability
    This vulnerability exists in the WebKit navigation handling within the browser. If the app is installed and running, the affected code is active regardless of specific configuration
    Affected if The installed version is below 151.3.1, meaning the browser contains the vulnerable WebKit navigation code

A user is affected if Mozilla Focus for iOS or Mozilla Klar for iOS is installed with a version number lower than 151.3.1, as the UXSS vulnerability in WebKit navigation handling is present in those versions.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to 151.3.1 or later
Fixed in 151.3.1
Interim mitigation

Update Focus for iOS and Klar for iOS to version 151.3.1 or later to remediate this vulnerability.

Recommended fix High confidence

Focus for iOS 151.3.1 / Klar for iOS 151.3.1

  1. 1. Open the App Store on the iOS device
  2. 2. Search for "Focus" or "Klar" depending on which app is installed
  3. 3. Verify the installed version by checking the app store listing or device settings
  4. 4. If the current version is below 151.3.1, tap the Update button to upgrade to version 151.3.1 or later
  5. 5. Alternatively, enable automatic app updates in iOS Settings > App Store > Automatic Downloads to ensure future updates are applied

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Focus Scoped from the published advisory
  • Consultation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
4.0 hours of engineering $750
Get the upgrade done

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 locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-11799 — 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 sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-11799 in production — separate from our analysis above.

No notes yet

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What this is

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.

What belongs here
  • 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