CVE-2016-4643
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 · uneditedIn iOS before 9.3.3, tvOS before 9.2.2, and OS X El Capitan before v10.11.6 and Security Update 2016-004, a validation issue existed in the parsing of 407 responses. This issue was addressed through improved response validation.
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 validation vulnerability existed in the parsing of HTTP 407 (Proxy Authentication Required) responses in iOS, tvOS, and OS X El Capitan. The insufficient validation during proxy response parsing could allow a man-in-the-middle attacker to trigger unexpected behavior or potentially execute arbitrary code via specially crafted 407 responses.
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< 9.2.2< 9.3.3>= 10.11.0, < 10.11.6CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:L/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 iOS version on iPhone or iPadGo to Settings > General > About and look at the Version field (e.g., 9.3.2)Affected if Version is less than 9.3.3 AND proxy authentication may be used
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Check tvOS version on Apple TVGo to Settings > General > About and look at the Version field (e.g., 9.2.1)Affected if Version is less than 9.2.2 AND proxy authentication may be used
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Check macOS El Capitan versionClick Apple menu > About This Mac and look at the version number (e.g., 10.11.5)Affected if Version starts with 10.11.0 through 10.11.5 AND proxy authentication may be used
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Check if HTTP proxy is configured on iOSGo to Settings > Wi-Fi, tap your network, then check HTTP Proxy settings under the HTTP PROXY fieldAffected if Proxy is set to Manual or Automatic (authenticated proxy) - if Proxy is Off, the 407 response parsing vulnerability does not apply
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Check if HTTP proxy is configured on macOSOpen System Preferences > Network, select your network service, click Advanced > Proxies tabAffected if Any HTTP or HTTPS proxy is enabled, particularly with authentication required - if all proxy settings are unchecked, the 407 response parsing vulnerability does not apply
You are affected if your OS version is below 9.3.3 (iOS), below 9.2.2 (tvOS), or between 10.11.0 and 10.11.5 (OS X El Capitan), AND you have an authenticated HTTP proxy configured.
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 data9.2.29.3.310.11.6
Apply Apple security updates: iOS 9.3.3 or later, tvOS 9.2.2 or later, OS X El Capitan v10.11.6 or Security Update 2016-004. Prioritize devices with direct internet exposure or those on untrusted networks.
- Consultation4.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-4643 — 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-2016-4643 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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- Version or environment caveats, and links to real fixes
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