CVE-2021-1847
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 · uneditedA memory corruption issue was addressed with improved validation. This issue is fixed in macOS Big Sur 11.3, Security Update 2021-002 Catalina, Security Update 2021-003 Mojave. Opening a maliciously crafted file may lead to unexpected application termination or 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 · moderate confidenceMemory corruption vulnerability in macOS file handling components. Opening a maliciously crafted file triggers memory corruption that can lead to arbitrary code execution. The vulnerability was fixed in macOS Big Sur 11.3 and Security Updates for earlier macOS versions.
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= 10.14= 10.14.0= 10.14.1= 10.14.2= 10.14.3= 10.14.4= 10.14.5= 10.14.6= 10.15= 10.15.1= 10.15.2= 10.15.3>= 11.0, < 11.3CVSS 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 installed macOS versionClick Apple menu > About This Mac. The version number is displayed below the macOS name.Affected if The version shows 10.14.x, 10.15.x, or 11.0-11.2.x (anything before 11.3)
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Confirm macOS build version for precisionIn About This Mac, click the version number to reveal the build number (e.g., 20A2411). Compare against Apple's security update documentation for your specific version.Affected if Running a build released before the security updates (2021-002 for Catalina, 2021-003 for Mojave, or before 11.3 for Big Sur)
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Verify system is unpatchedOpen System Preferences > Software Update to confirm no security updates have been installed.Affected if No security updates from 2021 have been applied, or Software Update shows no updates available on a vulnerable version
You are affected if your macOS version is 10.14.x, 10.15.x, or 11.0-11.2.x and no security updates have been installed since 2021.
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.
dbcve · scoped11.3
Apply the relevant Apple security update (macOS Big Sur 11.3, Security Update 2021-002 for Catalina, or Security Update 2021-003 for Mojave) to vulnerable systems.
macOS Big Sur 11.3 or Security Update 2021-002 (Catalina) or Security Update 2021-003 (Mojave)
- Identify your current macOS version from Apple menu > About This Mac
- For macOS Big Sur 11.0-11.2: Upgrade to macOS Big Sur 11.3 by checking for software updates via System Preferences > Software Update
- For macOS Catalina: Install Security Update 2021-002 through System Preferences > Software Update
- For macOS Mojave (10.14.x): Install Security Update 2021-003 through System Preferences > Software Update
- Restart the system when prompted to complete the installation
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,424.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-1847 — 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-2021-1847 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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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.
- 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