CVE-2021-1784
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 permissions issue existed in DiskArbitration. This was addressed with additional ownership checks. This issue is fixed in macOS Big Sur 11.3, Security Update 2021-002 Catalina, Security Update 2021-003 Mojave. A malicious application may be able to modify protected parts of the file system.
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 confidenceA permissions bypass vulnerability in macOS DiskArbitration framework allowed a malicious local application to modify protected parts of the file system due to missing ownership validation checks before disk operations.
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, <= 10.14.5>= 10.15, <= 10.15.5= 10.14.6= 10.15.6= 10.15.7>= 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
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
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.
-
Determine installed macOS versionRun 'sw_vers -productVersion' in Terminal, or go to Apple menu > About This Mac to view the version numberAffected if The displayed version falls within the affected ranges: 10.14.x, 10.15.x, or 11.0-11.2.x
-
Confirm full version numberIf running 10.14.x or 10.15.x, check the specific build version by running 'sw_vers -buildVersion' to confirm whether it matches the unpatched security update stateAffected if The build version corresponds to an update level prior to the Security Update 2021-002 (Catalina) or Security Update 2021-003 (Mojave)
-
Verify DiskArbitration framework availabilityThe vulnerability exists in the DiskArbitration framework. Confirm the system has this framework by checking /System/Library/Frameworks/DiskArbitration.framework existsAffected if The framework is present (which it is by default on all affected macOS versions)
The environment is affected if the installed macOS version is 10.14 through 10.14.6, 10.15 through 10.15.7, or 11.0 through 11.2.x and the relevant security updates have not been applied.
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 macOS security update: macOS Big Sur 11.3, Security Update 2021-002 (Catalina), or Security Update 2021-003 (Mojave) depending on the installed OS version.
macOS Big Sur 11.3 or later, Security Update 2021-002 (Catalina), Security Update 2021-003 (Mojave)
- Identify current macOS version via Apple menu > About This Mac
- For macOS Big Sur (11.x) systems: Upgrade to macOS 11.3 or later via System Preferences > Software Update
- For macOS Catalina (10.15.x) systems: Apply Security Update 2021-002 via System Preferences > Software Update
- For macOS Mojave (10.14.x) systems: Apply Security Update 2021-003 via System Preferences > Software Update
- Verify the security update was successfully installed by checking System Preferences > Security & Privacy > General
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-2021-1784 — 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-2021-1784 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
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.
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