SafariWeb browser · Apple
CVE-2018-4266
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 race condition was addressed with additional validation. This issue affected versions prior toiVersions prior to: OS 11.4.1, tvOS 11.4.1, watchOS 4.3.2, Safari 11.1.2, iTunes 12.8 for Windows, iCloud for Windows 7.6.
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 race condition vulnerability in multiple Apple products (iOS, tvOS, watchOS, Safari, iTunes, iCloud for Windows) that could allow improper access or manipulation due to timing issues in concurrent operations. The fix implemented additional validation checks to ensure proper synchronization.
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
SafariWeb browser
< 11.1.2< 11.4.1< 11.4.1< 4.3.2< 7.6< 12.8CVSS 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
- None
- Availability
- High
CVSS:3.0/AV:N/AC:H/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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Check Safari version on macOSOpen Safari, click Safari menu > About Safari. The version number is displayed next to the Safari logo.Affected if Version is earlier than 11.1.2
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Check iOS version on iPhone or iPadOpen Settings app > General > About. The version number is displayed under 'Version'.Affected if Version is earlier than 11.4.1
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Check tvOS version on Apple TVOpen Settings app > General > About. The version number is displayed next to 'tvOS'.Affected if Version is earlier than 11.4.1
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Check watchOS version on Apple WatchOpen Watch app on paired iPhone > General > About. The version number is displayed under 'watchOS'.Affected if Version is earlier than 4.3.2
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Check iTunes for Windows versionOpen iTunes, click Help > About iTunes. The version number is displayed in the dialog box.Affected if Version is earlier than 12.8
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Check iCloud for Windows versionOpen iCloud, click the gear icon > About iCloud. The version number is displayed in the window.Affected if Version is earlier than 7.6
Your environment is affected if any of the installed Apple products (Safari, iOS, tvOS, watchOS, iTunes for Windows, or iCloud for Windows) match a version earlier than the respective threshold (11.1.2, 11.4.1, 11.4.1, 4.3.2, 12.8, or 7.6).
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 data4.3.27.611.1.2
Update all affected Apple devices and software to versions OS 11.4.1+, tvOS 11.4.1+, watchOS 4.3.2+, Safari 11.1.2+, iTunes 12.8+ for Windows, or iCloud 7.6+ for Windows.
Fix this in Safari
Scoped from the published advisory
- Consultation2.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,480.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-4266 — 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-2018-4266 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