dbcve.org
IpadosOperating system · Apple

CVE-2021-1817

HIGH · 8.8 CVSS v3.1 Published 2021-09-08
Fix available
A fix is available. Upgrade to 7.4 / 11.3 or later.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable 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
A memory corruption issue was addressed with improved state management. This issue is fixed in macOS Big Sur 11.3, iOS 14.5 and iPadOS 14.5, watchOS 7.4, tvOS 14.5. Processing maliciously crafted web content may lead to arbitrary code execution.

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

This is a memory corruption vulnerability in WebKit (Apple's browser engine) affecting macOS Big Sur, iOS/iPadOS, watchOS, and tvOS. The vulnerability allows arbitrary code execution when a user processes maliciously crafted web content. The fix involved improved state management to prevent the memory corruption.

MitigationApply the vendor-supplied patches by updating affected devices to macOS Big Sur 11.3+, iOS/iPadOS 14.5+, watchOS 7.4+, or tvOS 14.5+. Organizations should deploy these updates through their MDM or patch management infrastructure.

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
IpadosOperating system
Affected:< 14.5
Iphone OsOperating system
Affected:< 14.5
macOSOperating system
Affected:>= 11.0, < 11.3
TvosOperating system
Affected:< 14.5
WatchosOperating system
Affected:< 7.4

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
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 checks

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

  1. Identify the Apple device and operating system type
    Determine whether the system is macOS, iOS, iPadOS, watchOS, or tvOS. On macOS, run 'sw_vers' or check System Preferences > About. On mobile devices, check Settings > General > About.
    Affected if The device runs any of the affected Apple operating systems listed in the CVE.
  2. Check the installed macOS version
    Run 'sw_vers -productVersion' in Terminal on macOS, or view System Preferences > About. Look for version numbers like 11.0, 11.1, 11.2, or 11.2.x.
    Affected if The macOS version is 11.0, 11.1, 11.2, or 11.2.x (versions 11.0 through 11.2.x are affected; 11.3 and later are fixed).
  3. Check the installed iOS or iPadOS version
    Open Settings > General > About on the iPhone or iPad. Note the version number displayed (for example, 14.4, 14.4.1, 14.4.2).
    Affected if The iOS or iPadOS version is below 14.5 (versions 14.0 through 14.4.x are affected).
  4. Check the installed watchOS or tvOS version
    On Apple Watch, open the Watch app on iPhone > My Watch > General > About, or go to Settings > General > About on the watch itself. On Apple TV, go to Settings > General > About.
    Affected if The watchOS version is below 7.4 or the tvOS version is below 14.5.
  5. Confirm WebKit is in use
    Verify that Safari or any third-party browser/app that uses the WebKit rendering engine is being used. WebKit is the default engine for Safari and many apps on Apple platforms.
    Affected if The device runs an affected OS version AND processes untrusted web content through Safari or any WebKit-based application.

The environment is affected if any Apple device runs macOS 11.0-11.2.x, iOS/iPadOS below 14.5, watchOS below 7.4, or tvOS below 14.5, and the WebKit browser engine is used to process web content.

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.

dbcve · scoped
Upgrade available Upgrade to 7.4 / 11.3 / 14.5 or later
Fixed in 7.411.314.5
Interim mitigation

Apply the vendor-supplied patches by updating affected devices to macOS Big Sur 11.3+, iOS/iPadOS 14.5+, watchOS 7.4+, or tvOS 14.5+. Organizations should deploy these updates through their MDM or patch management infrastructure.

Recommended fix High confidence

Upgrade to iOS 14.5 / iPadOS 14.5 / macOS Big Sur 11.3 / tvOS 14.5 / watchOS 7.4 as appropriate for your device

  1. For iOS devices: Go to Settings > General > Software Update, then download and install iOS 14.5
  2. For iPadOS devices: Go to Settings > General > Software Update, then download and install iPadOS 14.5
  3. For macOS devices: Open System Preferences > Software Update, or go to the Apple menu > System Preferences > Software Update, then download and install macOS Big Sur 11.3
  4. For tvOS devices: Go to Settings > System > Software Updates > Update Software, then download and install tvOS 14.5
  5. For watchOS devices: On the iPhone, open the Watch app, go to My Watch > General > Software Update, then download and install watchOS 7.4
Caveat Major OS updates may introduce compatibility issues with older applications; verify critical apps are supported before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Ipados Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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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-2021-1817 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