dbcve.org
Mac Os XOperating system · Apple

CVE-2021-30865

HIGH · 7.8 CVSS v3.1 Published 2021-08-24
Fix available
A fix is available. Upgrade to 10.15.7 / 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
An out-of-bounds read was addressed with improved input validation. This issue is fixed in macOS Big Sur 11.6, Security Update 2021-005 Catalina. A malicious application may be able to execute arbitrary code with kernel privileges.

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-2021-30865 is a kernel-level out-of-bounds read vulnerability in macOS that allows a malicious local application to escalate privileges and execute arbitrary code with kernel privileges. The vulnerability was addressed through improved input validation in macOS Big Sur 11.6 and Security Update 2021-005 for Catalina.

MitigationApply the appropriate macOS security updates (Big Sur 11.6 or Security Update 2021-005 Catalina) to all affected systems. This is a local privilege escalation vulnerability requiring user-level code execution first, but the high CVSS score reflects the severe impact of kernel-level compromise.

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:< 10.15.7= 10.15.7
macOSOperating system
Affected:>= 11.0, < 11.6

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. Identify macOS version
    Click the Apple menu > About This Mac. The version number appears below the macOS name.
    Affected if The version shows 10.15.7 (any build) or 11.0 through 11.5.x (any build)
  2. Confirm macOS Catalina patch level
    If running macOS 10.15.x, run: sw_vers -buildVersion. Compare the build number against 19H1323 (Catalina Security Update 2021-005) or later.
    Affected if Running 10.15.7 with build version earlier than 19H1323, or any earlier 10.15.x release
  3. Confirm macOS Big Sur patch level
    If running macOS 11.x, run: sw_vers -buildVersion. Compare the build number against 20G165 (Big Sur 11.6) or later.
    Affected if Running 11.0 through 11.5.x with build version earlier than 20G165
  4. Verify kernel patch state
    Run: uname -a && sysctl kern.osproductversion. This displays the kernel version for reference against Apple's security content.
    Affected if Kernel version remains at 10.15.7 or 11.0-11.5.x without corresponding security update applied

A system is affected if it runs macOS Catalina at any version including 10.15.7 without Security Update 2021-005, or macOS Big Sur 11.0-11.5 without the 11.6 update.

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 10.15.7 / 11.6 or later
Fixed in 10.15.711.6
Interim mitigation

Apply the appropriate macOS security updates (Big Sur 11.6 or Security Update 2021-005 Catalina) to all affected systems. This is a local privilege escalation vulnerability requiring user-level code execution first, but the high CVSS score reflects the severe impact of kernel-level compromise.

Recommended fix High confidence

macOS Big Sur 11.6 or Security Update 2021-005 for Catalina

  1. Check the current macOS version by clicking Apple menu > About This Mac
  2. If running macOS Big Sur (11.x), update to macOS 11.6 or later via System Preferences > Software Update
  3. If running macOS Catalina 10.15.7, apply Security Update 2021-005 via System Preferences > Software Update
  4. After updating, restart the system to ensure the kernel patch is fully applied

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

Fix this in Mac Os X Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2021-30865 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