CVE-2018-4174
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 · uneditedAn issue was discovered in certain Apple products. iOS before 11.3 is affected. macOS before 10.13.4 is affected. The issue involves the "Mail" component. It allows man-in-the-middle attackers to read S/MIME encrypted messages by leveraging an inconsistency in the user interface.
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 confidenceThis is a UI inconsistency vulnerability in the Mail component where S/MIME encrypted messages can be intercepted by man-in-the-middle attackers. The issue stems from the user interface failing to properly validate or display encryption status, allowing attackers to read supposedly encrypted messages.
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< 11.3< 10.13.4CVSS 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
- High
- Integrity
- None
- Availability
- None
CVSS:3.0/AV:N/AC:H/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 checksWork through these to decide whether this CVE applies to you.
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Check your iOS versionGo to Settings > General > About on iPhone/iPad and look at the Version fieldAffected if Version is lower than 11.3
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Check your macOS versionClick Apple menu > About This Mac and look at the version numberAffected if Version is lower than 10.13.4
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Verify S/MIME is configured in MailOn iOS: go to Settings > Mail > Account > Advanced > S/MIME and check if enabled. On macOS: open Mail > Preferences > Accounts > Account Settings > Advanced to see if S/MIME certificates are configuredAffected if S/MIME is enabled or a certificate is assigned for email signing/encryption
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Confirm receipt of S/MIME encrypted messagesSend or receive an encrypted email using S/MIME and observe whether the encryption indicator (lock icon) appears correctly in the message viewAffected if Encryption indicator fails to show or shows inconsistent status despite using S/MIME
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Assess MITM exposure riskReview network environment for potential interception points (untrusted WiFi, proxies) and verify whether sensitive encrypted emails could have been interceptedAffected if Running vulnerable OS version with S/MIME enabled on untrusted networks
You are affected if your iOS is below 11.3 or macOS is below 10.13.4 AND you use S/MIME encryption in Mail, as the UI may not properly display encryption status allowing potential interception.
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 data10.13.411.3
Apply vendor patches by updating iOS to version 11.3 or later and macOS to version 10.13.4 or later to resolve the S/MIME UI inconsistency.
- Consultation1.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2018-4174 — 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-2018-4174 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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