dbcve.org
IpadosOperating system · Apple

CVE-2021-30843

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 CoreText font parsing logic allows arbitrary code execution when processing a maliciously crafted dfont (data font) file. The vulnerability stems from insufficient validation checks during dfont file processing, enabling a specially crafted file to trigger memory corruption and execute arbitrary code in the context of the parsing application.

MitigationApply vendor patches by updating affected devices to iOS 14.8+/15+, iPadOS 14.8+/15+, macOS Big Sur 11.6+/Security Update 2021-005+, tvOS 15+, or watchOS 8+ as appropriate. Implement file-type restrictions and disable automatic font loading from untrusted sources as a defense-in-depth measure.

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/iPadOS version
    Go to Settings > General > About > Version on iPhone or iPad. Compare the version number to the affected ranges: < 14.8 for iPadOS and iOS.
    Affected if The installed iOS or iPadOS version is lower than 14.8
  2. Check macOS version
    Click Apple menu > About This Mac. Compare the macOS version to affected ranges: 10.15.0 through 10.15.6, 10.15.7, or 11.0 through 11.5.x.
    Affected if The installed macOS version is 10.15.x (excluding 10.15.7+, which is patched), or 11.0-11.5.x
  3. Check tvOS version
    Go to Settings > General > About > Version on Apple TV. Compare to affected range: < 15.0.
    Affected if The installed tvOS version is lower than 15.0
  4. Check watchOS version
    Open the Watch app on iPhone, go to General > About > Watch Version. Compare to affected range: < 8.0.
    Affected if The installed watchOS version is lower than 8.0
  5. Identify font processing activity
    Review installed applications that handle font files, particularly dfont files. Check if any applications automatically process fonts from untrusted sources or email attachments.
    Affected if Applications that parse dfont files using CoreText are in regular use, and the OS version falls within the affected ranges above

A user is affected if their device runs any iOS/iPadOS < 14.8, macOS 10.15.x (except 10.15.7+), macOS 11.0-11.5.x, tvOS < 15.0, or watchOS < 8.0, and they process dfont files through applications that use CoreText font parsing.

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 vendor patches by updating affected devices to iOS 14.8+/15+, iPadOS 14.8+/15+, macOS Big Sur 11.6+/Security Update 2021-005+, tvOS 15+, or watchOS 8+ as appropriate. Implement file-type restrictions and disable automatic font loading from untrusted sources as a defense-in-depth measure.

Recommended fix High confidence

iOS 14.8 / iPadOS 14.8 / macOS Big Sur 11.6 / Security Update 2021-005 Catalina / tvOS 15 / iOS 15 / iPadOS 15 / watchOS 8

  1. For iPhone/iPad: Go to Settings > General > Software Update and install iOS 14.8 or iPadOS 14.8 (or iOS 15/iPadOS 15 if desired)
  2. For macOS: Go to System Preferences > Software Update and install macOS Big Sur 11.6 (or Security Update 2021-005 for Catalina 10.15.7)
  3. For Apple TV: Go to Settings > System > Software Updates and install tvOS 15
  4. For Apple Watch: Go to the Watch app on iPhone > My Watch > General > Software Update and install watchOS 8
  5. Ensure the device is connected to Wi-Fi and power during the update process
  6. Back up important data before performing major version upgrades (iOS 15, iPadOS 15, tvOS 15, watchOS 8)
Caveat iOS 15, iPadOS 15, tvOS 15, and watchOS 8 are major version updates with potential new features and UI changes; iOS 14.8 and macOS 11.6 are recommended minimal updates if staying on the same major version is preferred

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

Fix this in Ipados Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA3.0 h
16.0 hours of engineering $2,820
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,512.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-30843 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2021-30843 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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