CVE-2020-9956
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 · uneditedAn out-of-bounds read was addressed with improved input validation. This issue is fixed in macOS Big Sur 11.0.1, tvOS 14.0, macOS Big Sur 11.1, Security Update 2020-001 Catalina, Security Update 2020-007 Mojave, watchOS 7.0, iOS 14.0 and iPadOS 14.0. Processing a maliciously crafted font 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 confidenceAn out-of-bounds read vulnerability exists in Apple's font processing subsystem due to insufficient input validation. When a device processes a maliciously crafted font file, the lack of proper bounds checking allows reading beyond allocated memory buffers, potentially enabling arbitrary code execution.
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< 14.0.< 14.0>= 10.14, < 10.14.6>= 10.15, < 10.15.7= 10.14.6= 10.15.7>= 11.0, < 11.1.0< 14.0< 7.0CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Check macOS version on the deviceRun 'sw_vers -productVersion' in Terminal to get the exact macOS version numberAffected if The version is 10.14.0 through 10.14.5, 10.14.6, 10.15.0 through 10.15.6, 10.15.7, or 11.0.0 (any build before 11.1.0)
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Check if macOS is running a vulnerable Big Sur releaseRun 'sw_vers -productVersion' and verify the exact build. The affected version is 11.0.x (any release prior to 11.1.0)Affected if The macOS version shows 11.0.x (for example, 11.0, 11.0.1) without the 11.1.0 security update applied
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Check iOS or iPadOS version on mobile devicesOn the device, go to Settings > General > About to view the iOS version, or use Apple Configurator or MDM tools for remote checkingAffected if The iOS/iPadOS version is 13.x or any version below 14.0
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Check tvOS version on Apple TV devicesUse Apple Configurator, MDM software, or the TV app to check the tvOS version, or access Settings > General > About on the Apple TVAffected if The tvOS version is any release below 14.0 (such as 13.x versions)
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Check watchOS version on Apple WatchOn iPhone, open the Watch app and navigate to General > About to see the watchOS version, or check via Apple ConfiguratorAffected if The watchOS version is any release below 7.0
The device is affected if it is running any macOS version from 10.14.x (prior to 10.14.6), 10.15.x (prior to 10.15.7), or 11.0.x (prior to 11.1.0); or any iOS/iPadOS, tvOS, or watchOS version below 14.0/7.0 respectively.
Generated from the published advisory. Verify against your own configuration.
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 data7.010.14.610.15.7
Apply the vendor-supplied security updates: macOS Big Sur 11.0.1/11.1, tvOS 14.0, watchOS 7.0, iOS/iPadOS 14.0, Security Update 2020-001 Catalina, and Security Update 2020-007 Mojave to remediate the font parsing vulnerability.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-9956 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-9956 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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