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Iphone OsOperating system · Apple

CVE-2018-4166

HIGH · 7.0 CVSS v3.0 Published 2018-04-03
Fix available
A fix is available. Upgrade to 4.3 / 10.13.4 or later.
See remediation →
73/100
Remediation priority · Elevated
No privileges

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
An issue was discovered in certain Apple products. iOS before 11.3 is affected. macOS before 10.13.4 is affected. tvOS before 11.3 is affected. watchOS before 4.3 is affected. The issue involves the "NSURLSession" component. A race condition allows attackers to execute arbitrary code in a privileged context via a crafted app.

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 confidence

A race condition in the NSURLSession component in iOS before 11.3, macOS before 10.13.4, tvOS before 11.3, and watchOS before 4.3 allows a crafted malicious app to execute arbitrary code in a privileged context.

MitigationApply vendor-supplied OS updates: upgrade iOS to 11.3 or later, macOS to 10.13.4 or later, tvOS to 11.3 or later, and watchOS to 4.3 or later.

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
Iphone OsOperating system
Affected:< 11.3
Mac Os XOperating system
Affected:< 10.13.4
TvosOperating system
Affected:< 11.3
WatchosOperating system
Affected:< 4.3

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
Local
Complexity
High
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/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 checks

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

  1. Check iOS version on iPhone or iPad
    Go to Settings > General > About on the device and note the Version number
    Affected if Version is below 11.3 (e.g., 11.2.x or earlier)
  2. Check macOS version on Mac
    Click the Apple menu > About This Mac and record the version shown (e.g., 10.13.3)
    Affected if Version is below 10.13.4
  3. Check tvOS version on Apple TV
    Go to Settings > General > About > Version on the Apple TV
    Affected if Version is below 11.3
  4. Check watchOS version on Apple Watch
    Open the Watch app on paired iPhone, go to General > About and check the watchOS version
    Affected if Version is below 4.3

Your device is affected if its OS version falls below the safe threshold for your platform (iOS 11.3, macOS 10.13.4, tvOS 11.3, or watchOS 4.3), since the NSURLSession race condition exists in the OS itself.

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.

From vendor data
Upgrade available Upgrade to 4.3 / 10.13.4 / 11.3 or later
Fixed in 4.310.13.411.3
Interim mitigation

Apply vendor-supplied OS updates: upgrade iOS to 11.3 or later, macOS to 10.13.4 or later, tvOS to 11.3 or later, and watchOS to 4.3 or later.

Fix this in Iphone Os Scoped from the published advisory
  • Consultation2.0 h
  • Testing1.0 h
  • Review / QA2.0 h
5.0 hours of engineering $910
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Scan for this in your stack

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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-2018-4166 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