CVE-2016-4657
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 · uneditedWebKit in Apple iOS before 9.3.5 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted web site.
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 confidenceMemory corruption vulnerability (use-after-free) in WebKit rendering engine affecting Safari on iOS versions prior to 9.3.5. Exploitation occurs through maliciously crafted websites, allowing remote attackers to execute arbitrary code or cause denial of service.
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< 9.3.5CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/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 checksWork through these to decide whether this CVE applies to you.
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Check iOS version on the deviceGo to Settings > General > About on the iOS device and look at the 'Version' field, or use MDM/mobile device management tools to query device inventoryAffected if The version displayed is below 9.3.5 (for example, 9.3.4, 9.3.3, 9.2.x, etc.)
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Identify the device model and iOS combinationQuery the device through MDM, Apple Configurator, or iTunes to retrieve both the model identifier and the installed iOS versionAffected if The device is running any iOS version prior to 9.3.5 regardless of model
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Confirm Safari is present on the deviceCheck that the Safari browser application is installed on the iOS device (it is pre-installed by default on all iPhones)Affected if Safari exists on the device (this is always true for consumer iOS devices)
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Determine if the device can receive Apple updatesAttempt to check for software updates via Settings > General > Software Update or query MDM to see if the device is still receiving security patchesAffected if The device shows no available updates or is labeled as 'unsupported' indicating it cannot be updated to 9.3.5 or later
The device is affected if it is running any version of iOS prior to 9.3.5 and has Safari installed, as the vulnerable WebKit component is bundled with iOS.
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.
dbcve · scoped9.3.5
Update affected iOS devices to version 9.3.5 or later. Implement mobile device management (MDM) policies to enforce OS updates and restrict browsing to trusted sources until patches are applied.
iOS 9.3.5
- Back up your iOS device data using iTunes or iCloud before upgrading
- Connect your device to a computer and open iTunes
- Check for updates by clicking "Check for Update" in iTunes
- Download and install iOS 9.3.5 when prompted
- Alternatively, go to Settings > General > Software Update on the device and download iOS 9.3.5
- Ensure the device remains connected to power during the update process
- After the update completes, verify the iOS version is 9.3.5 in Settings > General > About
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-4657 — 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-2016-4657 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