dbcve.org
SafariWeb browser · Apple

CVE-2020-27918

HIGH · 7.8 CVSS v3.1 Published 2020-12-08
Fix available
A fix is available. Upgrade to 11.0.1 / 11.5 or later.
See remediation →
81/100
Remediation priority · High
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 use after free issue was addressed with improved memory management. This issue is fixed in macOS Big Sur 11.0.1, watchOS 7.1, iOS 14.2 and iPadOS 14.2, iCloud for Windows 11.5, Safari 14.0.1, tvOS 14.2, iTunes 12.11 for Windows. 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

Use-after-free vulnerability in WebKit affecting Safari and other Apple products. Processing maliciously crafted web content can lead to arbitrary code execution due to improper memory management when handling freed memory references.

MitigationApply vendor-supplied patches: iOS 14.2, iPadOS 14.2, macOS Big Sur 11.0.1, watchOS 7.1, tvOS 14.2, Safari 14.0.1, iCloud for Windows 11.5, or iTunes 12.11 for Windows.

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
SafariWeb browser
Affected:< 14.0.1
FedoraOperating system
Affected:= 32= 33= 34
Debian LinuxOperating system
Affected:= 10.0
IcloudApplication
Affected:< 11.5
ItunesApplication
Affected:< 12.11
IpadosOperating system
Affected:< 14.2
Iphone OsOperating system
Affected:< 14.2
macOSOperating system
Affected:< 11.0.1

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
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/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 WebKit-using Apple product
    Determine if the target system runs Safari, iOS, iPadOS, macOS, iTunes for Windows, or iCloud for Windows. On Apple devices check Settings > General > About. On macOS check Apple menu > About This Mac. On Windows check Start menu for iTunes or iCloud.
    Affected if Any of these products are installed on the system
  2. Check Safari version on macOS
    Open Safari and go to Safari menu > About Safari. Note the version number displayed (e.g., 14.0 or 13.1.2).
    Affected if The version shown is earlier than 14.0.1
  3. Check macOS version
    Click Apple menu > About This Mac. The version number appears below the macOS name (e.g., 11.0 or 10.15.7).
    Affected if The macOS version is earlier than 11.0.1 (e.g., 10.15.x or earlier)
  4. Check iOS or iPadOS version on Apple mobile devices
    Open Settings > General > About on the iPhone or iPad. Note the version number (e.g., 14.1 or 13.7).
    Affected if The iOS or iPadOS version is earlier than 14.2
  5. Check iTunes for Windows version
    Open iTunes on Windows, then go to Help > About iTunes. Note the version number in the dialog window.
    Affected if The iTunes version is earlier than 12.11

You are affected if any WebKit-based Apple product on your system has a version number lower than the fixed versions (Safari 14.0.1, macOS 11.0.1, iOS/iPadOS 14.2, iTunes 12.11, iCloud 11.5).

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 11.0.1 / 11.5 / 12.11 or later
Fixed in 11.0.111.512.11
Interim mitigation

Apply vendor-supplied patches: iOS 14.2, iPadOS 14.2, macOS Big Sur 11.0.1, watchOS 7.1, tvOS 14.2, Safari 14.0.1, iCloud for Windows 11.5, or iTunes 12.11 for Windows.

Fix this in Safari Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

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-2020-27918 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