dbcve.org
IpadosOperating system · Apple

CVE-2021-30842

HIGH · 7.8 CVSS v3.1 Published 2021-10-19
Fix available
A fix is available. Upgrade to 8.0 / 11.6 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
This issue was addressed with improved checks. This issue is fixed in iOS 14.8 and iPadOS 14.8, macOS Big Sur 11.6, Security Update 2021-005 Catalina, tvOS 15, iOS 15 and iPadOS 15, watchOS 8. Processing a maliciously crafted dfont file 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

A vulnerability in Apple operating systems allows arbitrary code execution when processing a maliciously crafted dfont font file. The issue stems from insufficient validation checks during dfont file parsing, which can be exploited to execute arbitrary code via a specially crafted font file.

MitigationApply the available security updates for affected Apple products (iOS 14.8+/15+, iPadOS 14.8+/15+, macOS Big Sur 11.6+, tvOS 15, watchOS 8) and avoid opening untrusted dfont files from unknown sources.

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:< 14.8
Iphone OsOperating system
Affected:< 14.8
Mac Os XOperating system
Affected:>= 10.15, <= 10.15.6= 10.15.7
macOSOperating system
Affected:>= 11.0, < 11.6
TvosOperating system
Affected:< 15.0
WatchosOperating system
Affected:< 8.0

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. Check iOS or iPadOS version
    Go to Settings > General > About > Version on the device
    Affected if The version is lower than 14.8 (e.g., 14.7.x or earlier)
  2. Check macOS Catalina version
    Click Apple menu > About This Mac > Version (for macOS 10.15.x)
    Affected if The version is 10.15, 10.15.1, 10.15.2, 10.15.3, 10.15.4, 10.15.5, 10.15.6, or 10.15.7
  3. Check macOS Big Sur version
    Click Apple menu > About This Mac > Version (for macOS 11.x)
    Affected if The version is 11.0, 11.1, 11.2, 11.3, 11.4, or 11.5 (versions 11.6 and later are fixed)
  4. Check tvOS version
    Go to Settings > General > About > Version on Apple TV
    Affected if The version is lower than 15.0 (e.g., 14.7.x or earlier)
  5. Check watchOS version
    Open the Watch app on iPhone > General > About on the paired watch
    Affected if The version is lower than 8.0 (e.g., 7.x or earlier)

The device is affected if the installed OS version falls within any of the vulnerable ranges: iOS/iPadOS < 14.8, macOS 10.15.x, macOS 11.0-11.5, tvOS < 15.0, or watchOS < 8.0.

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 8.0 / 11.6 / 14.8 or later
Fixed in 8.011.614.8
Interim mitigation

Apply the available security updates for affected Apple products (iOS 14.8+/15+, iPadOS 14.8+/15+, macOS Big Sur 11.6+, tvOS 15, watchOS 8) and avoid opening untrusted dfont files from unknown sources.

Recommended fix High confidence

iOS 14.8/iPadOS 14.8, macOS Big Sur 11.6, Security Update 2021-005 Catalina, tvOS 15, watchOS 8 (or iOS 15/iPadOS 15 as alternatives)

  1. Identify the device type (iPhone, iPad, Mac, Apple TV, Apple Watch) and current OS version
  2. Back up important data before updating
  3. For iPhone/iPad: Go to Settings > General > Software Update and upgrade to iOS 14.8/iPadOS 14.8 or iOS 15/iPadOS 15
  4. For Mac: Go to System Preferences > Software Update and upgrade to macOS Big Sur 11.6, or apply Security Update 2021-005 for macOS Catalina
  5. For Apple TV: Go to Settings > System > Software Updates and upgrade to tvOS 15
  6. For Apple Watch: On iPhone, open Watch app > My Watch > General > Software Update and upgrade to watchOS 8
  7. Verify the update was successful by checking the OS version in Settings
Caveat iOS 15, iPadOS 15, tvOS 15, and watchOS 8 introduced significant UI changes and may have app compatibility issues; iOS 14.8 provides a less disruptive alternative for users on iOS 14

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 / QA2.0 h
20.0 hours of engineering $3,500
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,600.

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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-2021-30842 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