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IcloudApplication · Apple

CVE-2020-3909

CRITICAL · 9.8 CVSS v3.1 Published 2020-04-01
Fix available
A fix is available. Upgrade to 6.2 / 7.18 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 buffer overflow was addressed with improved bounds checking. This issue is fixed in iOS 13.4 and iPadOS 13.4, macOS Catalina 10.15.4, tvOS 13.4, watchOS 6.2, iTunes for Windows 12.10.5, iCloud for Windows 10.9.3, iCloud for Windows 7.18. Multiple issues in libxml2.

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 confidence

A buffer overflow vulnerability in libxml2, a widely-used XML parsing library, was addressed with improved bounds checking. This critical flaw (CVSS 9.8) affects multiple Apple products and could allow remote code execution or denial of service via specially crafted XML content.

MitigationApply the vendor-supplied patches by updating to iOS 13.4+/iPadOS 13.4+, macOS 10.15.4+, tvOS 13.4+, watchOS 6.2+, iTunes 12.10.5+, or iCloud for Windows 10.9.3+/7.18+. If immediate patching is not possible, restrict or sanitize XML input from untrusted sources and isolate affected systems.

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
IcloudApplication
Affected:< 7.18>= 10.9, < 10.9.3
ItunesApplication
Affected:< 12.10.5
IpadosOperating system
Affected:< 13.4
Iphone OsOperating system
Affected:< 13.4
Mac Os XOperating system
Affected:< 10.15.4
TvosOperating system
Affected:< 13.4
WatchosOperating system
Affected:< 6.2
Sun Zfs Storage Appliance Kit SoftwareApplication
Affected:= 8.8

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
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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. Check macOS version
    Open Apple menu > About This Mac to view the macOS version number
    Affected if Version is earlier than 10.15.4
  2. Check iOS or iPadOS version
    Go to Settings > General > About on the iOS/iPadOS device
    Affected if Version is earlier than 13.4
  3. Check tvOS or watchOS version
    Open Settings > General > About on Apple TV or Apple Watch
    Affected if tvOS version is earlier than 13.4 or watchOS version is earlier than 6.2
  4. Check iTunes version (Windows or older macOS)
    Open iTunes, then go to Help > About iTunes
    Affected if Version is earlier than 12.10.5
  5. Check iCloud for Windows version
    Open iCloud, click the gear icon, and view the version number
    Affected if Version is earlier than 7.18, or between 10.9 and 10.9.3 (inclusive)
  6. Check Oracle ZFS Storage Appliance Kit version
    Use the Oracle ZFS administrative interface or run the system version command via SSH
    Affected if Version is exactly 8.8

The environment is affected if any of the installed Apple products (iOS, iPadOS, macOS, tvOS, watchOS, iTunes, iCloud for Windows) or Oracle ZFS Storage Appliance Kit matches an affected version range listed in the CVE.

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 6.2 / 7.18 / 10.9.3 or later
Fixed in 6.27.1810.9.3
Interim mitigation

Apply the vendor-supplied patches by updating to iOS 13.4+/iPadOS 13.4+, macOS 10.15.4+, tvOS 13.4+, watchOS 6.2+, iTunes 12.10.5+, or iCloud for Windows 10.9.3+/7.18+. If immediate patching is not possible, restrict or sanitize XML input from untrusted sources and isolate affected systems.

Recommended fix High confidence

iOS 13.4+, iPadOS 13.4+, macOS 10.15.4+, tvOS 13.4+, watchOS 6.2+, iTunes 12.10.5, iCloud 7.18 or 10.9.3

  1. Identify which affected Apple product(s) are installed (iCloud, iTunes, iPadOS, iPhone OS, macOS, tvOS, or watchOS)
  2. For Windows systems with iCloud: Upgrade to version 7.18 or 10.9.3 (depending on which branch is in use)
  3. For Windows systems with iTunes: Upgrade to version 12.10.5
  4. For iPadOS devices: Upgrade to version 13.4 or later
  5. For iPhone devices: Upgrade to version 13.4 or later
  6. For Mac computers: Upgrade to macOS Catalina 10.15.4 or later
  7. For Apple TV devices: Upgrade to tvOS 13.4 or later
  8. For Apple Watch devices: Upgrade to watchOS 6.2 or later
Caveat Standard Apple OS upgrades may require compatible hardware; verify device compatibility before upgrading

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

Fix this in Icloud Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,760
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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-2020-3909 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