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Mac Os XOperating system · Apple

CVE-2021-30739

HIGH · 7.8 CVSS v3.1 Published 2021-09-08
Fix available
A fix is available. Upgrade to 11.4 or later.
See remediation →
80/100
Remediation priority · High
Zero-click

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
A local attacker may be able to elevate their privileges. This issue is fixed in macOS Big Sur 11.4, Security Update 2021-003 Catalina, Security Update 2021-004 Mojave. A memory corruption issue was addressed with improved validation.

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

CVE-2021-30739 is a local privilege escalation vulnerability in macOS stemming from memory corruption that was addressed through improved validation. A local attacker with the ability to execute code on the target system could exploit this to elevate their privileges to root or kernel level. The vulnerability affects macOS Mojave, Catalina, and Big Sur prior to their respective security updates.

MitigationApply the appropriate macOS security update: Big Sur 11.4, Security Update 2021-003 for Catalina, or Security Update 2021-004 for Mojave. This is a critical patch for systems with local user access.

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
Mac Os XOperating system
Affected:>= 10.14.0, <= 10.14.5>= 10.15, <= 10.15.6= 10.14.6= 10.15.7
macOSOperating system
Affected:>= 11.0.1, < 11.4

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/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 installed macOS version via System Preferences
    Open Apple menu > About This Mac. The version number is displayed under the macOS name (e.g., 'macOS Big Sur 11.3.1' or 'macOS Catalina 10.15.7').
    Affected if The displayed version falls within 10.14.0-10.14.5, 10.14.6, 10.15-10.15.6, 10.15.7, or 11.0.1-11.3.x.
  2. Check installed macOS version via command line
    Run 'sw_vers' in Terminal. The 'ProductVersion' line shows the exact macOS version (e.g., '10.15.7' or '11.3').
    Affected if The version matches any of the affected ranges listed above.
  3. Check for installed security updates
    Open System Preferences > Software Update. Look for any installed security updates. On Big Sur, click 'Additional info' next to the version to see update details.
    Affected if No security updates from 2021 (specifically 2021-003 for Catalina, 2021-004 for Mojave, or 11.4 for Big Sur) are installed.
  4. Verify kernel extension loading status (optional context)
    Run 'kextstat | grep -i apple' in Terminal to list loaded Apple kernel extensions. This vulnerability involves memory corruption in privileged operations.
    Affected if The system is running a vulnerable macOS version AND has local user access (the exploit requires local code execution).

The system is affected if it runs macOS versions 10.14.0-10.14.5, 10.14.6, 10.15-10.15.6, 10.15.7, or 11.0.1-11.3.x AND lacks the corresponding 2021 security updates.

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 11.4 or later
Fixed in 11.4
Interim mitigation

Apply the appropriate macOS security update: Big Sur 11.4, Security Update 2021-003 for Catalina, or Security Update 2021-004 for Mojave. This is a critical patch for systems with local user access.

Recommended fix High confidence

macOS Big Sur 11.4+ or install Security Update 2021-003 (Catalina) / Security Update 2021-004 (Mojave)

  1. Check current macOS version by clicking Apple menu > About This Mac
  2. For macOS Big Sur (11.x) users: Upgrade to macOS Big Sur 11.4 or later via System Preferences > Software Update
  3. For macOS Catalina (10.15.x) users: Install Security Update 2021-003 via System Preferences > Software Update
  4. For macOS Mojave (10.14.x) users: Install Security Update 2021-004 via System Preferences > Software Update
  5. After updating, verify the fix by checking that the security update is listed in System Preferences > Software Update
Caveat Standard macOS upgrade considerations apply - backup important data before updating

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

Fix this in Mac Os X Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
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Scan for this in your stack

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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-2021-30739 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